Gas turbine output learning circuit and combustion control device for gas turbine having the same

ABSTRACT

A gas turbine output learning circuit is configured to compute a current combustion gas temperature TIT at an inlet of a gas turbine by linear interpolation by use of two characteristic curves A and B respectively representing relations between a pressure ratio and an exhaust gas temperature in the cases of the combustion gas temperature at the inlet of the gas turbine at 1400° C. and 1500° C., then to compute ideal MW corresponding to this combustion gas temperature TIT at the inlet of the gas turbine by linear interpolation according to 1400° C.MW and 1500° C.MW (temperature controlled MW), and then to correct the 1400° C.MW and the 1500° C.MW so as to match the ideal MW with a measured gas turbine output (a power generator output).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a gas turbine output learning circuitand a combustion control device for a gas turbine having the gas turbineoutput learning circuit.

2. Description of the Related Art

A gas turbine including a gas turbine body, a combustor, a compressorhaving an inlet guide vane (IGV), and a fuel flow rate control valvecontrolling fuel supply to the fuel nozzle is provided with a combustioncontrol device for the gas turbine configured to control the fuel supplyto the fuel nozzle by controlling an aperture of the fuel flow ratecontrol valve, an IGV control device configured to control an apertureof the IGV, and so forth.

In the meantime, although details will be described later, concerningthe combustion control device for a gas turbine the inventors of thisinvention have disclosed a combustion control device for a gas turbinein non-published Japanese Patent Application No. 2005-266357. Thecombustion control device is capable of controlling a ratio of fuel suchas a pilot ratio or a degree of aperture of a combustor bypass valve inresponse to a combustion gas temperature at an inlet of a gas turbine inconformity to an original concept by computing a combustion load commandvalue (CLCSO) that is proportional to the combustion gas temperature atthe inlet of the gas turbine. Moreover, the inventors have alsodisclosed a concept of providing the combustion control device for a gasturbine with a learning circuit for a gas turbine output inconsideration of reduction in the gas turbine output (a power generatoroutput) attributable to deterioration in a performance of the gasturbine such as deterioration in a compression performance of acompressor.

Although details will be described later, this gas turbine outputlearning circuit in non-published Japanese Patent Application No.2005-266357 is configured to judge that the combustion gas temperatureat the inlet of the gas turbine reaches the maximum combustion gastemperature (such as 1500° C.) based on an exhaust gas temperature ofthe gas turbine body and a pressure ratio of the compressor. Thereafter,the gas turbine output learning circuit compares the gas turbine output(the power generator output) corresponding to the maximum combustion gastemperature computed by gas turbine output computing means with ameasured gas turbine output (a power generator output). Thereby, the gasturbine output learning circuit corrects the computed gas turbine outputto match with the measured gas turbine output. In addition tonon-published Japanese Patent Application No. 2005-266357, the prior artdocuments also include Japanese Patent Application Publication No.2004-190632 and Japanese Patent Application Publication No. Hei 8(1996)-246903.

However, the gas turbine output learning circuit disclosed innon-published Japanese Patent Application No. 2005-266357 is configuredto start learning after the judgment that the combustion gas temperatureat the inlet of the gas turbine reaches the maximum combustion gastemperature, that is, after the judgment that the gas turbine outputreaches a rated output (a rated load). Accordingly, a trouble may beincurred by a command from a central load dispatching center, forexample, in a case where the learning circuit is applied to a gasturbine which is configured to perform part-load operation frequently.

Specifically, in a case where the above-described gas turbine outputlearning circuit is applied to the combustion control device for the gasturbine which is often operated in a (part-load) state in which thecombustion gas temperature at the inlet of the gas turbine is adjustedto a lower temperature than the maximum combustion gas temperaturewithout raising the combustion gas temperature up to the maximumcombustion gas temperature, there is a risk that correction oftemperature controlled MW will not take place as the learning is neverstarted. Since this temperature controlled MW is used for computation ofthe CLCSO, if the temperature controlled MW is not corrected in spite ofreduction in the gas turbine output (the power generator output)attributable to deterioration in the performance of the gas turbine, theCLCSO may be deviated from the actual combustion gas temperature at theinlet of the gas turbine. In a case where the combustion control isperformed based on this CLCSO, there is a risk of causing combustionvibration.

SUMMARY OF THE INVENTION

The present invention has therefore been made in view of the foregoingcircumstance. It is an object of the present invention to provide a gasturbine output learning circuit capable of starting learning andperforming correction of a gas turbine output even in the case ofperforming part-load operation while not raising a combustion gastemperature at an inlet of the gas turbine up to the maximum combustiongas temperature. Moreover, it is also an object of the present inventionto provide a combustion control device for a gas turbine provided withthe gas turbine output learning circuit.

To attain the object, a gas turbine output learning circuit according toa first aspect, of the present invention is provided to a gas turbinewhich has a gas turbine body, a combustor, and a compressor. The gasturbine output learning circuit is characterized by including: means forcomputing a first exhaust gas temperature corresponding to a measuredpressure ratio according to a first characteristic curve representing arelation between the pressure ratio of the compressor and an exhaust gastemperature of the gas turbine body when a combustion gas temperature atan inlet of the gas turbine is adjusted to a first combustion gastemperature at the inlet of the gas turbine; means for computing asecond exhaust gas temperature corresponding to a measured pressureratio according to a second characteristic curve representing a relationbetween the pressure ratio and the exhaust gas temperature when thecombustion gas temperature at the inlet of the gas turbine is adjustedto a second combustion gas temperature at the inlet of the gas turbine,which is higher than the first combustion gas temperature at the inletof the gas turbine; means for computing a third combustion gastemperature at the inlet of the gas turbine corresponding to themeasured pressure ratio and a measured exhaust gas temperature by linearinterpolation according to the first combustion gas temperature at theinlet of the gas turbine, the second combustion gas temperature at theinlet of the gas turbine, the first exhaust gas temperature, the secondexhaust gas temperature, and the measured exhaust gas temperature; meansfor computing a third gas turbine output corresponding to the thirdcombustion gas temperature at the inlet of the gas turbine by linearinterpolation according to a first gas turbine output corresponding tothe first combustion gas temperature at the inlet of the gas turbine anda second gas turbine output corresponding to the second combustion gastemperature at the inlet of the gas turbine which are computed by gasturbine output computing means, the first combustion gas temperature atthe inlet of the gas turbine, the second combustion gas temperature atthe inlet of the gas turbine, and the third combustion gas temperatureat the inlet of the gas turbine; and means for correcting the first gasturbine output and the second gas turbine output which are used forcomputation of the third gas turbine output by comparing the third gasturbine output with a measured gas turbine output so as to match thethird gas turbine output with the measured gas turbine output.

Note that, the gas turbine output learning circuit includes eitherlearning-start judging means for judging that the measured gas turbineoutput is not less than a corrected value (an initial value) of thefirst gas turbine output corresponding to the first combustion gastemperature at the inlet of the gas turbine, or learning-start judgingmeans for judging that a combustion gas temperature at the inlet of thegas turbine reaches the combustion gas temperature at the inlet of thegas turbine according to the measured pressure ratio of the compressor,the exhaust gas temperature of the gas turbine body and the firstcharacteristic curve. The learning by this gas turbine output leaningcircuit may start after the judgment that the measured gas turbineoutput is not less than the corrected value (the initial value) of thefirst gas turbine output, or the judgment that the combustion gastemperature at the inlet of the gas turbine reaches the first combustiongas temperature at the inlet of the gas turbine, by any of thelearning-start judging means.

Further, in addition to the above-described judgments, thelearning-start judging means may also be configured to judge whether ornot a state where a variation (a variation in a load) in the measuredvalue of the gas turbine output (a power generator output) remainseither absent or within a predetermined range continuously for a certainperiod. The learning-start judging means is preferably configured tostart the learning after the aforementioned judgment and after thejudgment that the state where the variation (the variation in the load)in the gas turbine output (the power generator output) remains eitherabsent or within the predetermined range continuously for the certainperiod.

Meanwhile, a gas turbine output learning circuit of a second aspect ofthe present invention is characterized, in the gas turbine outputlearning circuit according to the first aspect, in which the means forcorrecting the first gas turbine output and the second gas turbineoutput is configured to correct the first gas turbine output and thesecond gas turbine output by calculating a correction efficient whileperforming any of a proportional-integral operation and an integraloperation of a deviation between the third gas turbine output and themeasured gas turbine output and multiplying each of the first gasturbine output and the second gas turbine output by this correctioncoefficient.

Meanwhile, a gas turbine output learning circuit of a third aspect ofthe present invention is characterized provides the gas turbine outputlearning circuit according to the second aspect, which further includesany of means for weighting the deviation between the third gas turbineoutput and the measured gas turbine output so as to increase a weightedcoefficient used for multiplication of the deviation in response to anincrease in a combustion load command value to render the combustion gastemperature at the inlet of the gas turbine computed by combustion loadcommand value computing means dimensionless, and means for weighting thedeviation so as to increase the weighted coefficient used formultiplication of the deviation in response to an increase in the thirdcombustion gas temperature at the inlet of the gas turbine.

Meanwhile, a combustion control device for a gas turbine according to afourth aspect of the present invention is fitted to a gas turbineprovided with a gas turbine body, a combustor having multiple types offuel nozzles, a compressor installed with an inlet guide vane, andmultiple fuel flow rate control valves for respectively controlling fuelsupplies to the multiple types of the fuel nozzles. The combustioncontrol device for a gas turbine according to a fourth aspect of thepresent invention is configured to control the fuel supplies to themultiple types of the fuel nozzles by controlling apertures of the fuelflow rate control valves. The combustion control device is characterizedby including gas turbine output computing means for computing a firstgas turbine output corresponding to a first combustion gas temperatureat an inlet of the gas turbine, a second gas turbine outputcorresponding to a second combustion gas temperature at the inlet of thegas turbine being higher than the first combustion gas temperature atthe inlet of the gas turbine, and a fourth gas turbine outputcorresponding to a fourth combustion gas temperature at the inlet of thegas turbine being lower than the second combustion gas temperature atthe inlet of the gas turbine according to an intake-air temperature ofthe compressor and an aperture of the inlet guide vane; and combustionload command computing means for computing a combustion load commandvalue to render the combustion gas temperature at the inlet of the gasturbine dimensionless by linear interpolation according to the secondgas turbine output, the fourth gas turbine output and a measured gasturbine output, in which the combustion control device controls the fuelsupplies to the multiple types of the fuel nozzles by determining ratiosof fuels to be supplied respectively to the multiple types of the fuelnozzles according to the combustion load command value computed by thecombustion load command computing means, and by controlling apertures ofthe fuel flow rate control valves according to the ratio of the fuels.Moreover, the combustion control device for a gas turbine ischaracterized by including a gas turbine output learning circuit whichhas: means for computing a first exhaust gas temperature correspondingto a measured pressure ratio according to a first characteristic curverepresenting a relation between the pressure ratio of the compressor andan exhaust gas temperature of the gas turbine body when a combustion gastemperature at an inlet of the gas turbine is adjusted to the firstcombustion gas temperature at the inlet of the gas turbine; means forcomputing a second exhaust gas temperature corresponding to a measuredpressure ratio according to a second characteristic curve representing arelation between the pressure ratio and the exhaust gas temperature whenthe combustion gas temperature at the inlet of the gas turbine isadjusted to the second combustion gas temperature at the inlet of thegas turbine; means for computing a third combustion gas temperature atthe inlet of the gas turbine corresponding to the measured pressureratio and a measured exhaust gas temperature by linear interpolationaccording to the first combustion gas temperature at the inlet of thegas turbine, the second combustion gas temperature at the inlet of thegas turbine, the first exhaust gas temperature, the second exhaust gastemperature, and the measured exhaust gas temperature; means forcomputing a third gas turbine output corresponding to the thirdcombustion gas temperature at the inlet of the gas turbine by linearinterpolation according to the first gas turbine output corresponding tothe first combustion gas temperature at the inlet of the gas turbine andthe second gas turbine output corresponding to the second combustion gastemperature at the inlet of the gas turbine, which are computed by thegas turbine output computing means, the first combustion gas temperatureat the inlet of the gas turbine, the second combustion gas temperatureat the inlet of the gas turbine, and the third combustion gastemperature at the inlet of the gas turbine; and means for correctingthe first gas turbine output and the second gas turbine output used forcomputation of the third gas turbine output so as to match with thethird gas turbine output with the measured gas turbine output bycomparing the third gas turbine output with a measured gas turbineoutput. Furthermore, the combustion control device is characterized inthat the second gas turbine output corrected by the gas turbine outputlearning circuit is used for computation of the combustion load commandvalue by the combustion load command value computing means.

Meanwhile, a combustion control device for a gas turbine of a fifthaspect of the present invention is characterized, in the combustioncontrol device for a gas turbine according to the fourth aspect, inwhich the means for correcting the first gas turbine output and thesecond gas turbine output in the gas turbine output learning circuit isconfigured to correct the first gas turbine output and the second gasturbine output by calculating a correction coefficient while performingany of a proportional-integral operation and an integral operation of adeviation between the third gas turbine output and the measured gasturbine output and by multiplying each of the first gas turbine outputand the second gas turbine output by this correction coefficient.

Meanwhile, a combustion control device for a gas turbine of a sixthaspect of the present invention is characterized, in the combustioncontrol device for a gas turbine according to the fifth aspect, whichfurther includes any of means for weighting a deviation between thethird gas turbine output and the measured gas turbine output so as toincrease a weighted coefficient used for multiplication of the deviationin response to an increase in a combustion load command value to renderthe combustion gas temperature at the inlet of the gas turbine computedby the combustion load command value computing means dimensionless, andmeans for weighting the deviation so as to increase the weightedcoefficient used for multiplication of the deviation in response to anincrease in the third combustion gas temperature at the inlet of the gasturbine.

Meanwhile, a combustion control device for a gas turbine of a seventhaspect of the present invention is characterized, in the combustioncontrol device for a gas turbine according to any of the fourth to sixthaspect, in which the gas turbine includes gas turbine bypassing meansfor bypassing compressed air to any of the combustor and the gas turbinebody, and the gas turbine output computing means computes the first gasturbine output, the second gas turbine output, and the fourth gasturbine output according to the intake-air temperature of thecompressor, the aperture of the inlet guide vane, and a turbine bypassratio equivalent to a ratio between a total amount of compressed air bythe compressor and a turbine bypass flow rate by the gas turbinebypassing means.

Meanwhile, a combustion control device for a gas turbine of an eighthaspect of the present invention is characterized, in the combustioncontrol device for a gas turbine according to any of the fourth toseventh aspects, in which the gas turbine output computing meanscomputes the first gas turbine output, the second gas turbine output,and the fourth gas turbine output according to the intake-airtemperature of the compressor, the aperture of the inlet guide vane, andan atmospheric pressure ratio equivalent to a ratio between the intakepressure of the compressor and a standard atmospheric pressure, oraccording to the intake-air temperature of the compressor, the apertureof the inlet guide vane, the turbine bypass ratio, and the atmosphericpressure ratio.

The gas turbine output learning circuit according to the first aspectincludes means for computing the first exhaust gas temperaturecorresponding to the measured pressure ratio according to the firstcharacteristic curve representing the relation between the pressureratio of the compressor and the exhaust gas temperature of the gasturbine body when the combustion gas temperature at the inlet of the gasturbine is adjusted to the first combustion gas temperature at the inletof the gas turbine; means for computing the second exhaust gastemperature corresponding to the measured pressure ratio according tothe second characteristic curve representing the relation between thepressure ratio and the exhaust gas temperature when the combustion gastemperature at the inlet of the gas turbine is adjusted to the secondcombustion gas temperature at the inlet of the gas turbine, which ishigher than the first combustion gas temperature at the inlet of the gasturbine; means for computing the third combustion gas temperature at theinlet of the gas turbine corresponding to the measured pressure ratioand the measured exhaust gas temperature by linear interpolationaccording to the first combustion gas temperature at the inlet of thegas turbine, the second combustion gas temperature at the inlet of thegas turbine, the first exhaust gas temperature, the second exhaust gastemperature, and the measured exhaust gas temperature; means forcomputing the third gas turbine output corresponding to the thirdcombustion gas temperature at the inlet of the gas turbine by linearinterpolation according to the first gas turbine output corresponding tothe first combustion gas temperature at the inlet of the gas turbine andthe second gas turbine output corresponding to the second combustion gastemperature at the inlet of the gas turbine which are computed by gasturbine output computing means, the first combustion gas temperature atthe inlet of the gas turbine, the second combustion gas temperature atthe inlet of the gas turbine, and the third combustion gas temperatureat the inlet of the gas turbine; and means for correcting the first gasturbine output and the second gas turbine output which are used forcomputation of the third gas turbine output by comparing the third gasturbine output with a measured gas turbine output so as to match thethird gas turbine output with the measured gas turbine output. Thus,even in a case where the second combustion gas temperature at the inletof the gas turbine is equal to the maximum combustion gas temperature,for example, it is possible to start learning and to perform correctionof the gas turbine output when continuing part-load operation withoutraising the combustion gas temperature at the inlet of the gas turbineup to the maximum combustion gas temperature.

Meanwhile, according to the gas turbine output learning circuit of thesecond aspect, the means for correcting the first gas turbine output andthe second gas turbine output is configured to correct the first gasturbine output and the second gas turbine output by calculating thecorrection efficient while performing any of the proportional-integraloperation and an integral operation of a deviation between the third gasturbine output and the measured gas turbine output and multiplying eachof the first gas turbine output and the second gas turbine output bythis correction coefficient. Thus, it is possible to correct the firstgas turbine output and the second gas turbine output easily andreliably.

Meanwhile, the gas turbine output learning circuit of the third aspectfurther includes any of the means for weighting the deviation betweenthe third gas turbine any of means for weighting the deviation betweenthe third gas turbine output and the measured gas turbine output so asto increase the weighted coefficient used for multiplication of thedeviation in response to an increase in the combustion load commandvalue to render the combustion gas temperature at the inlet of the gasturbine computed by combustion load command value computing meansdimensionless, and means for weighting the deviation so as to increasethe weighted coefficient used for multiplication of the deviation inresponse to the increase in the third combustion gas temperature at theinlet of the gas turbine. Thus, it is possible to correct the gasturbine output appropriately in response to the combustion gastemperature at the inlet of the gas turbine (that is, the gas turbineoutput) and thereby to correct the gas turbine output promptly whilereducing the learning time around the second combustion gas temperatureat the inlet of the gas turbine (such as the maximum combustion gastemperature).

The combustion control device for a gas turbine of the fourth aspectincludes means for computing the first exhaust gas temperaturecorresponding to the measured pressure ratio according to the firstcharacteristic curve representing a relation between the pressure ratioof the compressor and the exhaust gas temperature of the gas turbinebody when a combustion gas temperature at the inlet of the gas turbineis adjusted to the first combustion gas temperature at the inlet of thegas turbine; means for computing the second exhaust gas temperaturecorresponding to the measured pressure ratio according to the secondcharacteristic curve representing the relation between the pressureratio and the exhaust gas temperature when the combustion gastemperature at the inlet of the gas turbine is adjusted to the secondcombustion gas temperature at the inlet of the gas turbine; means forcomputing the third combustion gas temperature at the inlet of the gasturbine corresponding to the measured pressure ratio and the measuredexhaust gas temperature by linear interpolation according to the firstcombustion gas temperature at the inlet of the gas turbine, the secondcombustion gas temperature at the inlet of the gas turbine, the firstexhaust gas temperature, the second exhaust gas temperature, and themeasured exhaust gas temperature; means for computing the third gasturbine output corresponding to the third combustion gas temperature atthe inlet of the gas turbine by linear interpolation according to thefirst gas turbine output corresponding to the first combustion gastemperature at the inlet of the gas turbine and the second gas turbineoutput corresponding to the second combustion gas temperature at theinlet of the gas turbine, which are computed by the gas turbine outputcomputing means, the first combustion gas temperature at the inlet ofthe gas turbine, the second combustion gas temperature at the inlet ofthe gas turbine, and the third combustion gas temperature at the inletof the gas turbine; and means for correcting the first gas turbineoutput and the second gas turbine output used for computation of thethird gas turbine output so as to match with the third gas turbineoutput with the measured gas turbine output by comparing the third gasturbine output with a measured gas turbine output. Thus, even in a casewhere the second combustion gas temperature at the inlet of the gasturbine is equal to the maximum combustion gas temperature, for example,it is possible to start learning and to perform correction of the gasturbine output when continuing part-load operation without raising thecombustion gas temperature at the inlet of the gas turbine up to themaximum combustion gas temperature.

Moreover, since the second gas turbine output corrected by the gasturbine output learning circuit is used for computation of thecombustion load command value by the combustion load command valuecomputing means, it is possible to compute an accurate combustion loadcommand value (CLCSO) corresponding to an actual combustion gastemperature at the inlet of the gas turbine when continuing part-loadoperation without raising the combustion gas temperature at the inlet ofthe gas turbine up to the maximum combustion gas temperature.

Meanwhile, according to the combustion control device for a gas turbineof the fifth aspect, the means for correcting the first gas turbineoutput and the second gas turbine output in the gas turbine outputlearning circuit is configured to correct the first gas turbine outputand the second gas turbine output by finding the correction efficientwhile performing any of the proportional-integral operation and theintegral operation of the deviation between the third gas turbine outputand the measured gas turbine output and multiplying the first gasturbine output and the second gas turbine output by this correctioncoefficient respectively. Thus, it is possible to correct the first gasturbine output and the second gas turbine output easily and reliably.

Meanwhile, according to the combustion control device for a gas turbineof the sixth aspect, the gas turbine output learning circuit comprisesany of means for weighting a deviation between the third gas turbineoutput and the measured gas turbine output so as to increase a weightedcoefficient used for multiplication of the deviation in response to anincrease in a combustion load command value to render the combustion gastemperature at the inlet of the gas turbine computed by the combustionload command value computing means dimensionless, and means forweighting the deviation so as to increase the weighted coefficient usedfor multiplication of the deviation in response to an increase in thethird combustion gas temperature at the inlet of the gas turbine. Thus,it is possible to correct the gas turbine output appropriately inresponse to the combustion gas temperature at the inlet of the gasturbine (that is, the gas turbine output) and thereby to correct the gasturbine output promptly while reducing learning time around the secondcombustion gas temperature at the inlet of the gas turbine (such as themaximum combustion gas temperature).

Meanwhile, according to the combustion control device for a gas turbineof the seventh aspect, the combustion load command value is computed inconsideration of the turbine bypass ratio at the same time. Thus, it ispossible to perform control according to the combustion gas temperatureat the inlet of the gas turbine even in the case of the gas turbineprovided with the gas turbine bypassing means, and thereby to performappropriate combustion control.

Meanwhile, according to the combustion control device for a gas turbineof the eighth aspect, the combustion load command value can be computedin consideration of the atmospheric pressure ratio at the same time.Thus, it is possible to maintain relations between the combustion loadcommand value (the combustion gas temperature at the inlet of the gasturbine) and each of the fuel gas ratios appropriately, and thereby toperform appropriate combustion control.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention and wherein;

FIG. 1 is a view showing a schematic configuration of a gas turbineincluding a combustion control device for a gas turbine according to anembodiment of the present invention.

FIG. 2 is a view showing a structure of a combustor in the gas turbine.

FIG. 3 is a block diagram showing a pilot manifold portion of a pilotfuel supply line in the gas turbine.

FIG. 4 is an overall block diagram showing the combustion control devicefor a gas turbine according to the embodiment of the present invention.

FIG. 5 is a block diagram showing an outline of a process flow in thecombustion control device for a gas turbine.

FIG. 6 is a graph showing a relation between a combustion gastemperature TIT at an inlet of the gas turbine and a CLCSO.

FIG. 7 is a graph showing a relation between the CLCSO and a pilotratio.

FIG. 8 is a graph showing a relation between the CLCSO and a top hatratio.

FIG. 9 is a graph showing a relation between the CLCSO and a combustorbypass valve position command value.

FIG. 10 is a graph showing a relation between the combustion gastemperature TIT at the inlet of the gas turbine and a gas turbine output(a power generator output) in terms of various IGV apertures.

FIG. 11 is a graph showing a relation between an intake-air temperatureand the gas turbine output (the power generator output) in terms of thevarious IGV apertures.

FIG. 12 is a graph showing a relation between the power generator output(the gas turbine output) at a certain IGV aperture, a certain intake-airtemperature, a certain turbine bypass ratio and a certain atmosphericpressure ratio, and the CLCSO.

FIG. 13 is a graph showing the relation between the power generatoroutput (the gas turbine output) and the CLCSO relative to a variation inthe IGV aperture.

FIG. 14 is a graph showing the relation between the power generatoroutput (the gas turbine output) and the CLCSO relative to a variation inthe intake-air temperature.

FIG. 15 is a graph showing the relation between the power generatoroutput (the gas turbine output) and the CLCSO relative to a variation inthe turbine bypass ratio.

FIG. 16 is a block diagram showing a configuration of computation logicof the CLCSO in the combustion control device for a gas turbine.

FIG. 17 is a block diagram showing a configuration of a gas turbineoutput learning circuit according to non-published Japanese PatentApplication No. 2005-266357.

FIG. 18 is a graph of a characteristic curve showing a relation betweena pressure ratio and an exhaust gas temperature.

FIG. 19 is a block diagram showing a configuration of a gas turbineoutput learning circuit according to an embodiment of the presetinvention.

FIG. 20 is a graph of characteristic curves A and B showing relationsbetween a pressure ratio and an exhaust gas temperature.

FIG. 21 is a block diagram showing computation logic at 1400° C.MW.

FIG. 22 is a graph showing a relation between CLCSO and a weightedcoefficient.

FIG. 23 is a graph of characteristic curves A, B, C, and D showingrelations between the pressure ratio and the exhaust gas temperature.

FIG. 24 is a block diagram showing a configuration of computation logicof the combustor bypass valve position command value in the combustioncontrol device for a gas turbine.

FIG. 25 is a graph showing a relation between the CLCSO and weight ofintake-air temperature correction.

FIG. 26 is a graph showing a relation between the intake-air temperatureand a correction coefficient.

FIG. 27 is a block diagram showing a configuration of computation logicof a PLCSO in the combustion control device for a gas turbine.

FIG. 28 is a block diagram showing a configuration of computation logicof a THCSO in the combustion control device for a gas turbine.

FIG. 29 is a block diagram showing a configuration of computation logicof respective fuel flow rate control valve position command values inthe combustion control device for a gas turbine.

FIG. 30 is a graph showing a relation (a proportional relation) betweenthe PLCSO and a pilot fuel gas flow rate G_(fPL).

FIG. 31 is a graph showing a relation between a valve aperture and a Cvvalue.

FIG. 32 is a graph showing a relation (a proportional relation) betweenthe THCSO and a top hat fuel gas flow rate G_(fTH).

FIG. 33 is a graph showing a relation (a proportional relation) betweena MACSO and a main fuel gas flow rate G_(fMA).

FIG. 34 is a block diagram showing a configuration of fuel gastemperature correction logic in the combustion control device for a gasturbine.

FIG. 35 is a block diagram showing a configuration of manifold pressurecorrection logic in the combustion control device for a gas turbine.

FIG. 36 is a graph showing a relation between the power generator output(the gas turbine output) and a change rate.

FIG. 37 is a block diagram showing a configuration of computation logicof a manifold pressure in the combustion control device for a gasturbine.

FIG. 38 is a logic diagram showing a configuration of a learning circuitfor a nozzle Cv value in the combustion control device for a gasturbine.

FIG. 39 is a graph showing operating results of the gas turbineincluding the combustion control device for a gas turbine.

FIG. 40 is another graph showing operating results of the gas turbineincluding the combustion control device for a gas turbine.

FIG. 41 is still another graph showing operating results of the gasturbine including the combustion control device for a gas turbine.

FIG. 42 is still another graph showing operating results of the gasturbine including the combustion control device for a gas turbine.

FIG. 43 is still another graph showing operating results of the gasturbine including the combustion control device for a gas turbine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Now, an embodiment of the present invention will be described in detailwith reference to the accompanying drawings.

(Configuration)

Firstly, a configuration of a gas turbine will be described withreference to FIG. 1 to FIG. 3. As shown in FIG. 1, a gas turbine 1includes a gas turbine body 2, multiple combustors 3, and a compressor 4having a rotating shaft joined to a rotating shaft of the gas turbinebody 2. A power generator 5 is installed in this gas turbine 1 tocollectively constitute a gas turbine power generation facility. Arotating shaft of this power generator 5 is also joined to the rotatingshaft of the gas turbine body 2.

A fuel is combusted in each of the combustors 3 together with ahigh-pressure compressed air taken in and compressed by the compressor4. When the gas turbine body 2 is rotated by this combustion gas, thepower generator 5 is driven rotatively by this gas turbine body 2 togenerate power. The power generated by the power generator 5 istransmitted through an unillustrated power transmission system. Thecombustion gas (exhaust gas) discharged from the gas turbine body 2after working the gas turbine body 2 is carried through an exhaust line32 and released from an unillustrated stack to the air. An air-intakeamount of the compressor 4 in the course of this gas turbine drive iscontrolled by opening and closing inlet guide vanes (IGVs) 6 installedat an inlet of the compressor 4. The opening and closing drives of theIGVs 6 are carried out by an actuator 7 such as a servo motor, which isfitted to the IGVs 6. Aperture control of the IGVs 6 (drive control ofthe actuator 7) is performed by an unillustrated IGV control device.

Meanwhile, each of the combustors 3 is provided with a combustor bypassline 31 for causing the air compressed by the compressor 4 to bypass thecombustor 3. The combustor bypass line 31 is provided with a combustorbypass valve 8 for adjusting a bypassing flow rate of the compressedair. At the time of a low load, an aperture of the combustor bypassvalve 8 is increased and the bypassing flow rate of the compressed airis thereby increased in order to raise the fuel gas density and tostabilize combustion. In contrast, at the time of a high load, theaperture of the combustor bypass valve 8 is reduced and the bypassingflow rate of the compressed air is thereby reduced in order to decreaseNOx and the like. In this way, the amount of the compressed air to bemixed with the combustion gas is increased. Meanwhile, a turbine bypassline 9 for causing the air compressed by the compressor 4 to bypass thecombustor 3 and the gas turbine body 2 is provided in a space from anoutlet side of the compressor 4 to an outlet side (the exhaust line 32)of the gas turbine body 2. This turbine bypass line 9 is provided with aturbine bypass valve 10 for adjusting a turbine bypass flow rate of thecompressed air (gas turbine bypassing means). This valve is provided forthe purpose of adjusting an output pressure of the compressor 4 (acylinder pressure) and the like.

Each of the combustors 3 has a configuration as shown in FIG. 2. Asshown in FIG. 2, the combustor 3 includes multiple types of fuelnozzles, namely, main nozzles 26 as first fuel nozzles, a pilot nozzle25 as a second fuel nozzle, and top hat nozzles 27 as third fuelnozzles. The pilot nozzle 25 and the main nozzles 26 are disposed insidean inner cylinder 28, while the top hat nozzles 27 are disposed in aspace between the inner cylinder 28 and an outer cylinder 29.

The pilot nozzle 25 is a fuel nozzle for diffuse combustion targeted forachieving combustion stability and the like. The single pilot nozzle 25is provided at a central part of the inner cylinder 28. The main nozzle26 is a fuel nozzle for premixed combustion targeted for NOx reduction,which is designed to mix main fuel gas with the compressed air on anupstream side of a combustion portion and then to subject the mixed gasto combustion. The multiple main nozzles 26 are provided around thepilot nozzle 25. The top hat nozzle 27 is a fuel nozzle for premixedcombustion targeted for further NOx reduction, which is designed to mixtop hat fuel gas with the compressed air on an upstream side of the mainnozzles 26 and then to subject the mixed gas to combustion. The multipletop hat nozzles 27 are provided on the outer peripheral side of the mainnozzles 26.

Moreover, as shown in FIG. 1 and FIG. 2, a main fuel supply line 12, apilot fuel supply line 13, and a top hat fuel supply line 14 which arebranched off from a fuel gas supply line 11 connected to anunillustrated fuel tank or gas field are connected respectively to themain nozzles 26, the pilot nozzle 25, and the top hat nozzles 27 of eachof the combustors 3. The main fuel supply line 12 is provided with amain fuel pressure control valve 16 and a main fuel flow rate controlvalve 17 in the order from the upstream side. The pilot fuel supply line13 is provided with a pilot fuel pressure control valve 18 and a pilotfuel flow rate control valve 19 in the order from the upstream side.Moreover, the top hat fuel supply line 14 is provided with a top hatfuel pressure control valve 20 and a top hag fuel flow rate controlvalve 21 in the order from the upstream side.

A main manifold 22 of the main fuel supply line 12 is provided with amain manifold pressure gauge PX1 for measuring a pressure of the mainfuel gas inside the main manifold 22. A pilot manifold 23 of the pilotfuel supply line 13 is provided with a pilot manifold pressure gauge PX2for measuring a pressure of pilot fuel gas inside the pilot manifold 23.Moreover, a top hat manifold 24 of the top hat fuel supply line 14 isprovided with a top hat manifold pressure gauge PX3 for measuring apressure of the top hat fuel gas inside the top hat manifold 24.

Meanwhile, the main fuel supply line 12 is provided with a main fueldifferential pressure gauge PDX1 for measuring a main fuel gasdifferential pressure in front and on the back of the main fuel flowrate control valve 17. The pilot fuel supply line 13 is provided with apilot fuel differential pressure gauge PDX2 for measuring a pilot fuelgas differential pressure in front and on the back of the pilot fuelflow rate control valve 19. Moreover, the top hat fuel supply line 14 isprovided with a top hat fuel differential pressure gauge PDX3 formeasuring a top hat fuel gas differential pressure in front and on theback of the top hat fuel flow rate control valve 21.

As schematically shown in FIG. 3, the pilot manifold 23 is configured todistribute the pilot fuel gas, which is supplied through the pilot fuelsupply line 13, to the pilot nozzles 25 of the respective combustors 3.Although illustration is omitted therein, the main manifold 22 issimilarly configured to distribute the main fuel gas supplied throughthe main fuel supply line 12 to the main nozzles 26 of the respectivecombustors 3, and the top hat manifold 24 is also configured todistribute the top hat fuel gas supplied through the top hat fuel supplyline 14 to the top hat nozzles 27 of the respective combustors 3.

Meanwhile, the main fuel pressure control valve 16 is configured toadjust the main fuel gas differential pressure in front and on the backof the main fuel flow rate control valve 17, which is measured by themain fuel differential pressure gauge PDX1, to a constant value. Thepilot fuel pressure control valve 18 is configured to adjust the pilotfuel gas differential pressure in front and on the back of the pilotfuel flow rate control valve 19, which is measured by the pilot fueldifferential pressure gauge PDX2, to a constant value. Moreover, the tophat fuel pressure control valve 20 is configured to adjust the top hatfuel gas differential pressure in front and on the back of the top hatfuel flow rate control valve 21, which is measured by the top hat fueldifferential pressure gauge PDX3, to a constant value.

Furthermore, the main fuel flow rate control valve 17 is configured toadjust a flow rate of the main fuel gas which is supplied to the mainnozzles 26 of all of the combustors 3 through the main fuel supply line12. The pilot fuel flow rate control valve 19 is configured to adjust aflow rate of the pilot fuel gas which is supplied to the pilot nozzles25 of all of the combustors 3 through the pilot fuel supply line 13.Moreover, the top hat fuel flow rate control valve 21 is configured toadjust a flow rate of the top hat fuel gas which is supplied to the tophat nozzles 27 of all of the combustors 3 through the top hat fuelsupply line 14.

Meanwhile, as shown in FIG. 1, the fuel supply line 11 is provided witha fuel stop valve 15 and a fuel gas thermometer Tf. The fuel gasthermometer Tf measures the temperature of the fuel gas flowing in thefuel gas supply line 11 and outputs a measurement signal in terms ofthis fuel gas temperature to a gas turbine combustion control device 41(see FIG. 4) fitted to this gas turbine 1, and the like. Measurementsignals from the main manifold pressure gauge PX1, the pilot manifoldpressure gauge PX2, the top hat manifold pressure gauge PX3, the mainfuel differential pressure gauge PDX1, the pilot fuel differentialpressure gauge PDX2, and the top hat fuel differential pressure gaugePDX3 are also outputted to the gas turbine combustion control device 41and the like.

Moreover, the power transmission system of the power generator 5 isprovided with a power meter PW. An intake-air thermometer Ta, anintake-air pressure gauge PX4, and an intake-air flowmeter FX1 areprovided on the inlet side of the compressor 4, while a cylinderpressure gauge PX5 is provided on the outlet side of the compressor 4.The turbine bypass line 9 is provided with a turbine bypass flowmeterFX2. The exhaust line 32 is provided with an exhaust gas thermometer Th.

The power meter PW measures generated power (the power generator output:the gas turbine output) of the power generator 5 and outputs ameasurement signal of this power generator output (the gas turbineoutput) to the gas turbine combustion control device 41 and the like.The intake-air thermometer Ta measures the intake-air temperature in thecompressor 4 (the temperature of the air flowing into the compressor 4)and outputs a measurement signal of this intake-air temperature to thegas turbine combustion control device 41 and the like. The intake-airpressure gauge PX4 measures the intake-air pressure of the compressor 4(the pressure of the air flowing into the compressor 4) and outputs ameasurement signal of this intake-air pressure to the gas turbinecombustion control device 41 and the like. The intake-air flowmeter FX1measures the flow rate of the intake air flowing into the compressor 4and outputs a measurement signal of this intake-air flow rate to the gasturbine combustion control device 41 and the like. The cylinder pressuregauge PX5 measures the cylinder pressure representing the pressure ofthe compressed air to be ejected from the compressor 4 and outputs ameasurement signal of this cylinder pressure to the gas turbinecombustion control device 41 and the like. The turbine bypass flowmeterFX2 measures the turbine bypass flow rate of the compressed air flowingthrough the turbine bypass line 9 and outputs a measurement signal ofthis turbine bypass flow rate to the gas turbine combustion controldevice 41 and the like. The exhaust gas thermometer Th measures thetemperature of the exhaust gas discharged from the gas turbine body 2and outputs a measurement signal of this exhaust gas temperature to thegas turbine combustion control device 41 and the like.

Next, the gas turbine combustion control device 41 will be describedwith reference to FIG. 4 to FIG. 43. Note that, each of processingfunctions of the gas turbine combustion control device 41 is constructedin the form of software (computer programs) that is executed by acomputer. However, the present invention will not be limited only tothis configuration. It is also possible to construct the processingfunctions in the form of hardware.

As shown in FIG. 4, a power generator output command value transmittedfrom an unillustrated central load dispatching center, and an IGVaperture command value transmitted from the unillustrated IGV controldevice are inputted to the gas turbine combustion control device 41.Note that, the power generator output command value is not alwaysrequired to be transmitted from the central load dispatching center. Forexample, the power generator output command value may be set up by apower generator output setting device that is installed in the gasturbine power generation facility. Moreover, in this case, the IGVaperture command value is adopted as the IGV aperture used forcomputation of a CLCSO (a combustion load command) which is a commonparameter of the combustion control. However, the present invention willnot be limited only to this configuration. For example, in a case ofmeasuring the IGV aperture, it is possible to use this measurement valueinstead.

In addition, the power generator output measured by the power meter PW,the intake-air temperature measured by the intake-air thermometer Ta,the fuel gas temperature measured by the fuel gas thermometer Tf, theexhaust gas temperature measured by the exhaust gas thermometer Th, theintake-air flow rate measured by the intake-air flowmeter FX1, theturbine bypass flow rate measured by the turbine bypass flowmeter FX2,the main manifold pressure measured by the main manifold pressure gaugePX1, the pilot manifold pressure measured by the pilot manifold pressuregauge PX2, the top hat manifold pressure measured by the top hatmanifold pressure gauge PX3, the intake-air pressure measured by theintake-air pressure gauge PX4, the cylinder pressure measured by thecylinder pressure gauge PX5, the main fuel gas differential pressuremeasured by the main fuel differential pressure gauge PDX1, the pilotfuel gas differential pressure measured by the pilot fuel differentialpressure gauge PDX2, and the top hat fuel gas differential pressuremeasured by the top hat fuel differential pressure gauge PDX3 areinputted as actual measured values to the gas turbine combustion controldevice 41.

Thereafter, based on these input signals and the like, the gas turbinecombustion control device 41 calculates a main fuel flow rate controlvalve position command value for performing main fuel gas flow ratecontrol, a pilot fuel flow rate control valve position command value forperforming pilot fuel gas flow rate control, a top hat fuel flow ratecontrol valve position command value for performing top hat fuel gasflow rate control, and a combustor bypass valve position command valuefor performing combustion bypassing flow rate control.

An outline of a process flow in the gas turbine combustion controldevice 41 will be described with reference to FIG. 5. Firstly, the CLCSOis computed based on the power generator output, the IGV aperturecommand value, the intake-air temperature, a turbine bypass ratio (theturbine bypass flow rate/the intake-air flow rate) representing a ratiobetween the intake-air flow rate and the turbine bypass flow rate, andan atmospheric pressure ratio (an atmospheric pressure/a standardatmospheric pressure) representing a ratio between the atmosphericpressure and the standard atmospheric pressure. This CLCSO isproportional to a value obtained by rendering a combustion gastemperature at an inlet of a gas turbine (a temperature of the fuel gasat an inlet of the gas turbine body when the fuel gas flows from thecombustor 3 to the gas turbine body 2) dimensionless. In other words,the CLCSO is a value proportional to the combustion gas temperature atthe inlet of the gas turbine. Thereafter, a pilot ratio representing aratio of a pilot fuel gas flow rate (a weight flow rate) relative to atotal fuel gas flow rate (a weight flow rate), a top hat ratiorepresenting a ratio of a top hat fuel gas flow rate (a weight flowrate) relative to the total fuel gas flow rate (the weight flow rate),and a main ratio representing a ratio of a main fuel gas flow rate (aweight flow rate) relative to the total fuel gas flow rate (the weightflow rate) are calculated based on this CLCSO.

Subsequently, the weight flow rates, namely, the pilot fuel gas flowrate G_(fPL), the top hat fuel gas flow rate G_(fTH), and the main fuelgas flow rate G_(fMA) are calculated based on the pilot ratio, the tophat ratio, and the main ratio, respectively. Further, a Cv value of thepilot fuel flow rate control valve 19, a Cv value of the top hat fuelflow rate control valve 21, and a Cv value of the main fuel flow ratecontrol valve 17 are calculated based on the pilot fuel gas flow rateG_(fPL), the top hat fuel gas flow rate G_(fTH), and the main fuel gasflow rate G_(fMA), respectively. Then, the pilot fuel flow rate controlvalve position command value, the top hat fuel flow rate control valveposition command value, and the main fuel flow rate control valveposition command value are calculated based on the Cv value of the pilotfuel flow rate control valve 19, the Cv value of the top hat fuel flowrate control valve 21, and the Cv value of the main fuel flow ratecontrol valve 17, respectively. Meanwhile, in terms of the combustorbypass valve 8, the combustor bypass valve position command value iscalculated based on the CLCSO as well.

Next, the processing to be executed by the gas turbine combustioncontrol device 41 will be described in detail. In the following, theprocessing to calculate the CLCSO will be firstly described concerningthe processing of the gas turbine combustion control device 41. Then,the processing for calculating the respective valve position commandvalues based on this CLCSO will be described.

(Computation of CLCSO)

In order to formulate the pilot ratio, the top hat ratio, the mainratio, and the aperture of the combustor bypass valve into functions ofthe combustion gas temperature TIT at the inlet of the gas turbinerepresenting original concepts, the CLCSO formed by rendering thecombustion gas temperature TIT at the inlet of the gas turbinedimensionless is applied as a control parameter. For this reason, theCLCSO is computed to begin with. As shown in FIG. 6, the CLCSO isassumed to be proportional to the combustion gas temperature TIT at theinlet of the gas turbine (CLCSO∝TIT). In this respect, in theillustrated example, the CLCSO corresponding to the combustion gastemperature TIT at the inlet of the gas turbine of 700° C., which isdefined as a fourth combustion gas temperature at the inlet of the gasturbine, is assumed to be 0%. Meanwhile, the CLCSO corresponding to thecombustion gas temperature TIT at the inlet of the gas turbine of 1500°C., which is defined as a second combustion gas temperature at the inletof the gas turbine, is assumed to be 100%. The second combustion gastemperature is higher than the fourth combustion gas temperature. It isto be noted that the fourth combustion gas temperature at the inlet ofthe gas turbine as well as the second combustion gas temperature at theinlet of the gas turbine constituting the criteria for computing theCLCSO are not limited only to the 700° C. and 1500° C. It is possible toset up other temperatures as appropriate.

Moreover, a relation (a function) between the CLCSO and the pilot ratioas shown in FIG. 7 as an example, a relation (a function) between theCLCSO and the top hat ratio as shown in FIG. 8 as an example, and arelation (a function) between the CLCSO and the combustor bypass valveposition command value (BYCSO) as shown in FIG. 9 as an example are setup in advance. Relations of the combustion gas temperature TIT at theinlet of the gas turbine with the pilot ratio, the top hat ratio, andthe aperture of the combustor bypass valve can be obtained inpreliminary studies (in gas turbine designing processes). Accordingly,based on these relations, it is possible to set up the relations of theCLCSO with the pilot ratio, the top hat ratio, and the combustor bypassvalve position command value (BYCSO) as shown in FIG. 7 to FIG. 9 asexamples. Moreover, by calculating the pilot ratio, the top hat ratio,and the aperture of the combustor bypass valve by use of the computedCLCSO and the relations show in FIG. 7 to FIG. 9, the pilot ratio, thetop hat ratio, and the aperture of the combustor bypass valve areuniquely determined relative to the combustion gas temperature TIT atthe inlet of the gas turbine because the CLCSO is proportional to thecombustion gas temperature TIT at the inlet of the gas turbine(CLCSO∝TIT). That is, the pilot ratio, the top hat ratio, and theaperture of the combustion bypass valve become functions of the CLCSO(the combustion gas temperature TIT at the inlet of the gas turbine).Since the main ratio is calculated based on the pilot ratio and the tophat ratio (to be described later in detail), the main ratio also becomesa function of the CLCSO (the combustion gas temperature TIT at the inletof the gas turbine).

The CLCSO is computed based on the gas turbine output (the powergenerator output). Specifically, a relation between the combustion gastemperature TIT at the inlet of the gas turbine and the gas turbineoutput (the power generator output) in terms of various IGV apertures isshown in FIG. 10, and a relation between the intake-air temperature andthe gas turbine output (the power generator output) in terms of thevarious IGV apertures is shown in FIG. 11. As shown in FIG. 10 and FIG.11, in terms of the various intake-air temperature and various IGVapertures, it is possible to treat the combustion gas temperature TIT atthe inlet of the gas turbine is in the linear relation with the gasturbine output (the power generator output). Therefore, the combustiongas temperature TIT at the inlet of the gas turbine, i.e. the CLCSO isderived from the gas turbine output (the power generator output).

For this reason, a relation (a function) between the power generatoroutput (the gas turbine output) and the CLCSO is set up whileconsidering the IGV apertures and the intake-air temperatures shown inFIG. 12 and also considering the turbine bypass ratio and theatmospheric pressure (air pressure/standard atmospheric pressure: anaverage atmospheric pressure in a place where the gas turbine isinstalled is used as the standard atmospheric pressure, for example).

Specifically, a 700° C.MW value representing the power generator output(the gas turbine output) when the combustion gas temperature TIT at theinlet of the gas turbine is equal to 700° C. that is determined as thefourth combustion gas temperature at the inlet of the gas turbine, and a1500° C.MW value representing the power generator output (the gasturbine output) when the combustion gas temperature TIT at the inlet ofthe gas turbine is equal to 1500° C. that is determined as the secondcombustion gas temperature at the inlet of the gas turbine are set up inthe first place. Note that, the temperature of 1500° C. is the maximumcombustion gas temperature (an upper limit) determined in the gasturbine designing processes in terms of durability of the combustor 3and the gas turbine body 2. Since the temperature is adjusted not toexceed this value, the temperature of 1500° C. is also referred to as atemperature controlled MW. These temperatures of 700° C. and 1500° C.(the temperature controlled MW) can be calculated in the preliminarystudies (in the gas turbine designing processes).

Then, as shown in FIG. 12, the CLCSO relative to the 700° C.MW isdefined as 0% and the CLCSO relative to the 1500° C.MW value is definedas 100%. It is to be noted, however, that the 700° C.MW value and the1500° C.MW value are the values considering the IGV aperture, theintake-air temperature, the turbine bypass ratio, and the atmosphericpressure ratio. That is, these values respectively represent the powergenerator output (the gas turbine output) at the combustion gastemperature TIT at the inlet of the gas turbine of 700° C. and the powergenerator output (the gas turbine output) at the combustion gastemperature TIT at the inlet of the gas turbine of 1500° C. in terms ofa certain IGV aperture, a certain intake-air temperature, a certainturbine bypass ratio, and a certain pressure ratio.

In other words, as shown in FIG. 13 as an example, the relation betweenthe power generator output (the gas turbine output) and the CLCSO variesdepending on the IGV aperture (such as 0% (when an intake-air passage isnot completely closed), 50% or 100%). As shown in FIG. 14 as an example,the relation between the power generator output (the gas turbine output)and the CLCSO also varies depending on the intake-air temperature (suchas −10° C. and 40° C.). Moreover, as shown in FIG. 15 as an example, therelation between the power generator output (the gas turbine output) andthe CLCSO also varies depending on the turbine bypass ratio. Althoughillustration is omitted herein, the relation between the power generatoroutput (the gas turbine output) and the CLCSO also varies depending onthe atmospheric pressure ratio (such as 1.0 or 1.1).

For this reason, the 1500° C.MW values corresponding to the IGVaperture, the intake-air temperature, the turbine bypass ratio, and theatmospheric pressure are set up in advance. Table 1 shown belowexemplifies the preset 1500° C.MW values corresponding to the IGVaperture, the intake-air temperature, the turbine bypass ratio, and theatmospheric pressure ratio. The example shown in Tale 1 sets up the1500° C.MW values in the cases where the IGV aperture is equal to anyone of 0%, 50%, and 100%, the intake-air temperature is equal to any oneof −10° C. and 40° C., and the turbine bypass ratio is equal to 10%.These values are obtained in the preliminary studies (in the gas turbinedesigning processes). Note that, the 1500° C.MW value in the case wherethe turbine bypass ratio is equal to 0% is solely determined by the IGVaperture and the intake-air temperature. For example, the 1500° C.MWvalue is equal to 140 MW when the IGV aperture (the IGV aperturecommand) is equal to 100%, the intake-air temperature is equal to −10°C., and the turbine bypass ratio is equal to 0%, while the 1500° C.MWvalue is equal to 110 MW when the IGV aperture is equal to 100%, theintake-air aperture is equal to −10° C., and the turbine bypass ratio isequal to 10%.

TABLE 1 When TIT = 1500° C. (1500° C. MW) IGV aperture 0% 50% 100%Intake-air −10° C. 100 MW 120 MW 140 MW temperature (70 MW at (90 MW at(110 MW at turbine turbine turbine bypass ratio bypass ratio bypassratio equal to 10%) equal to 10%) equal to 10%)   40° C. 80 MW 100 MW120 MW (50 MW at (70 MW at (90 MW at turbine turbine turbine bypassratio bypass ratio bypass ratio equal to 10%) equal to 10%) equal to10%)

If any values of the IGV aperture, the intake-air temperature, and theturbine bypass ratio is different from those shown in Table 1 (when theIGV aperture is equal to 60%, the intake-air temperature is equal to 10°C., and the turbine bypass ratio is equal to 5%, for example), the 1500°C.MW value corresponding to the IGV aperture, the intake-airtemperature, and the turbine bypass ratio can be computed by linearinterpolation (interpolating calculation) by use of any of the 1500°C.MW values shown in Table 1.

Moreover, by multiplying the 1500° C.MW value considering the IGVaperture, the intake-air temperature, and the turbine bypass ratio bythe atmospheric pressure ratio, it is possible to compute the 1500° C.MWvalue while considering the atmospheric pressure ratio as well.

Although detailed explanation will be omitted herein, it is alsopossible to calculate the value considering the IGV aperture, theintake-air temperature, the turbine bypass ratio, and the atmosphericpressure ratio in a similar manner to the case of 1500° C.MW value.Table 2 shown below exemplifies the preset 700° C.MW valuescorresponding to the IGV aperture, the intake-air temperature, theturbine bypass ratio, and the atmospheric pressure ratio.

TABLE 2 When TIT = 700° C. (700° C. MW) IGV aperture 0% 50% 100%Intake-air −10° C. 5 MW 6 MW 7 MW temperature (3 MW at (4 MW at (5 MW atturbine turbine turbine bypass ratio bypass ratio bypass ratio equal to10%) equal to 10%) equal to 10%)   40° C. 3 MW 4 MW 5 MW (1 MW at (2 MWat (3 MW at turbine turbine turbine bypass ratio bypass ratio bypassratio equal to 10%) equal to 10%) equal to 10%)

Then, upon determination of the 700° C.MW and 1500° C.MW values whileconsidering the IGV aperture, the intake-air temperature, the turbinebypass ratio, and the atmospheric pressure ratio, the CLCSO is computedin accordance with the following formula (1) representing the linearinterpolation (interpolating calculation) formula based on the 700° C.MWand 1500° C.MW values and an actual measurement value of the gas turbineoutput (the power generator output):

$\begin{matrix}{{CLCSO}\mspace{11mu}(\%)\frac{\begin{matrix}{{{Actual}\mspace{14mu}{value}\mspace{14mu}{of}\mspace{14mu}{gas}}\mspace{14mu}} \\{{{turbine}\mspace{14mu}{output}\mspace{14mu}({MW})} - {700{^\circ}\mspace{14mu}{C.\mspace{14mu}{MW}}}}\end{matrix}}{{1500{^\circ}\mspace{14mu}{C.\mspace{14mu}{MW}}} - {700{^\circ}\mspace{20mu}{C\;.\mspace{14mu}{MW}}}} \times 100} & (1)\end{matrix}$

Now, an explanation will be made based on computation logic of the CLCSO(combustion load command computing means) shown in FIG. 16. First, afunction generator 51 as gas turbine output computing means computes the1500° C.MW value (the temperature controlled MW) as a second gas turbineoutput based on an actual measurement value of the intake-airtemperature, the IGV aperture command value, and the turbine bypassratio (a turbine bypass flow rate/intake-air flow rate) calculated bydividing an actual measurement value of a turbine bypass flow rate by anactual measurement value of an intake-air flow rate (corresponding to atotal amount of the compressed air) with a divider 53. That is, the1500° C.MW value is calculated while considering the IGV aperture, theintake-air temperature, and the turbine bypass ratio. The method ofcomputing this 1500° C.MW value has been described previously.

A function generator 52 as gas turbine output computing means computesthe 700° C.MW value as a fourth gas turbine output based on theintake-air temperature, the IGV aperture command value, and the turbinebypass ratio. That is, the 700° C.MW value is calculated whileconsidering the IGV aperture, the intake-air temperature, and theturbine bypass ratio. The method of computing this 700° C.MW value issimilar to the case of computing the 1500° C.MW value.

A divider 54 calculates the atmospheric pressure ratio (intake-airpressure/standard atmospheric pressure) by dividing an actualmeasurement value of an intake-air pressure (the atmospheric pressure)by the standard atmospheric pressure set up with a signal generator 61.A multiplier 55 multiplies the 1500° C.MW value calculated with thefunction generator 51 by the atmospheric pressure ratio calculated withthe divider 54, to calculate the 1500° C.MW value in consideration ofthe atmospheric pressure ratio as well. The 1500° C.MW value calculatedwith the multiplier 55 is outputted to a subtracter 57 through a gasturbine output learning circuit 201 functioning as learning means.Details of the learning circuit 201 will be described later. Amultiplier 56 multiplies the 700° C.MW value calculated with thefunction generator 52 by the atmospheric pressure ratio calculated withthe divider 54 to calculate the 700° C.MW value in consideration of theatmospheric pressure ratio as well.

The subtracter 57 subtracts the 700° C.MW value calculated with themultiplier 56 from the 1500° C.MW value calculated with the multiplier55 (or corrected by the gas turbine output learning circuit 201) (1500°C.MW-700° C.MW: see the formula (1)). A subtracter 58 subtracts the 700°C.MW value calculated with the multiplier 56 from the actual measurementvalue of the power generator output (the gas turbine output) (the actualmeasurement value of the power generator output (the gas turbine output)−700° C.MW: see the formula (1)).

Thereafter, a divider 59 divides a result of subtraction with thesubtracter 58 by a result of subtraction with the subtracter 57 (see theformula (1)). In this way, it is possible to compute the CLCSO. Notethat, to express the CLCSO in percentage, an output value from thedivider 59 should be multiplied by 100. A rate setter 60 outputs aninputted value from the divider 59 while restricting the value to agiven rate of change instead of directly outputting the inputted valueas the CLCSO in order to avoid the main fuel flow rate control valve 17and the like from frequently repeating opening and closing operationscaused by a small variation in the CLCSO attributable to a smallvariation in the gas turbine output (the power generator output) or thelike.

Incidentally, when the gas turbine 1 is operated for a long period,deterioration in the performance of the gas turbine 1 may be caused bydeterioration in a compression performance of the compressor 4 and thelike. As a consequence, the power generator output (the gas turbineoutput) starts declining. That is, in this case, the power generatoroutput (the gas turbine output) does not reach the given (such as arated) power generator output (gas turbine output) as shown in FIG. 10even when the combustion gas temperature TIT at the inlet of the gasturbine reaches 1500° C. As a result, the CLCSO may also decline and therelation between the CLCSO and the combustion gas temperature TIT at theinlet of the gas turbine may be deviated. Accordingly, the relations ofthe combustion gas temperature TIT at the inlet of the gas turbine withthe pilot ratio, the top hat ratio, the main ratio, and the aperture ofthe combustor bypass valve will be also deviated. Therefore, it isnecessary to reduce the value of 1500° C.MW (the temperature controlledMW) for computing the CLCSO as well.

For this reason, in the gas turbine combustion control device 41, thecomputation logic of the CLCSO also includes the learning circuit 201for 1500° C.MW value (the temperature controlled MW).

Now, the learning circuit 62 for the gas turbine output (the powergenerator output) disclosed in the above-mentioned non-publishedJapanese Patent Application No. 2005-266357 will be described withreference to FIG. 17 to begin with. This gas turbine output learningcircuit 62 firstly judges whether or not the combustion gas temperatureTIT at the inlet of the gas turbine reaches the maximum combustion gastemperature (1500° C.) before starting to learn the 1500° C.MW value(the temperature controlled MW). Accordingly, the gas turbine outputlearning circuit 62 judges whether or not a decline in the powergenerator output (the gas turbine output) is attributable todeterioration in characteristics of the gas turbine 1. Specifically,when the combustion gas temperature TIT at the inlet of the gas turbineis equal to the maximum combustion gas temperature (1500° C.), there isa relation between a pressure ratio of the compressor 4 (a ratio betweena pressure on the inlet side and a pressure on the outlet side of thecompressor 4) and the exhaust gas temperature of the gas turbine body 2(the temperature of the exhaust gas discharged from the gas turbine body2) as shown in FIG. 18. Therefore, the learning circuit 62 monitors apressure ratio (the cylinder pressure/the intake-air pressure) of thecompressor 4 obtained from the actual measurement value of theintake-air pressure and the actual measurement value of the cylinderpressure as well as the actual measurement value of the exhaust gastemperature. Moreover, the learning circuit 62 judges that thecombustion gas temperature TIT at the inlet of the gas turbine reachesthe maximum combustion gas temperature (1500° C.) when the pressureratio and the exhaust gas temperature satisfy the relation shown in FIG.18, and then starts learning.

In this case, the learning circuit 62 firstly calculates a deviation(the power generator output −1500° C.MW) between the 1500° C.MW value(the temperature controlled MW) after correction in terms of theatmospheric pressure ratio to be inputted from the multiplier 55 in thecomputation logic of the CLCSO shown in FIG. 16 and the actualmeasurement value of the gas turbine output (the power generator output)by use of a subtracter (a deviation operator) 63. A PI (proportion andintegration) controller 64 calculates a correction coefficient bysubjecting the deviation calculated with the subtracter (the deviationoperator) 63 to proportional and integral operations. A LOW limiter 65limits the correction coefficient (ranging from 0 to 1) operated withthe PI operator 64 to a range from 0.95 to 1. The reason for providingthe limited range of the correction coefficient as described above is toconsider an amount of presumable reduction in the power generator output(the gas turbine output) by normal deterioration in the performance ofthe gas turbine 1 and to prevent excessive correction attributable to anabnormal drop of the output from the gas turbine 1. A multiplier 66multiplies the correction coefficient by the 1500° C.MW value (thetemperature controlled MW) inputted from the multiplier 55, and outputsthe result of multiplication to the subtracter (the deviation operator)63.

By performing the processing as described above, the 1500° C.MW value(the temperature controlled MW) is corrected so as to match with theactual measurement value of the gas turbine output (the power generatoroutput). Then, the 1500° C.MW value (the temperature controlled MW)after the correction is outputted to the subtracter 57 in thecomputation logic of the CLCSO shown in FIG. 16 for use in thecalculation of the CLCSO. Note that, a lower value selector 67 selectsthe lower value out of the 1500° C.MW value (the temperature controlledMW) after the correction and the rated power generator output (the gasturbine output) set up in a signal generator 68, and outputs theselected value for various kinds of controls and monitor display and thelike.

However, as described previously, in the case where the gas turbine 1 isoften subjected to part-load operation, or specifically where theoperation of the gas turbine 1 is often continued while setting thecombustion gas temperature at the inlet of the gas turbine to a lowertemperature than the maximum combustion gas temperature without raisingthe temperature up to the maximum combustion gas temperature, this gasturbine output learning circuit 62 may incur a problem that the learningis never started and correction of the gas turbine output at the time ofcontrolling the temperature (the temperature controlled MW) never takesplace, even though the gas turbine output (the power generator output)is reduced due to deterioration in the performance of the gas turbine 1.

Therefore, in the present embodiment, the gas turbine combustion controldevice 41 includes the gas turbine output learning circuit 201 as shownin FIG. 19. Now, a configuration of this gas turbine output learningcircuit 201 will be described below with reference to FIG. 19 to FIG.23.

Two characteristic curves A and B as shown in FIG. 20 as an example arepreset in this gas turbine output learning circuit 201. In FIG. 20, thelateral axis indicates the pressure ratio of the compressor 4, and thelongitudinal axis indicates the exhaust gas temperature of the gasturbine body 2. The characteristic curves A and B may be set up in theform of mathematical expressions or set up (stored) in the format oftable data, for example.

The characteristic curve A serving as a first characteristic curve isthe characteristic curve that represents a relation between the pressureratio and the exhaust gas temperature when the combustion gastemperature at the inlet of the gas turbine is adjusted to 1400° C. (thepart load) as a first combustion gas temperature at the inlet of the gasturbine. The characteristic curve B serving as a second characteristiccurve is the characteristic curve that represents a relation between thepressure ratio and the exhaust gas temperature when the combustion gastemperature at the inlet of the gas turbine is adjusted to 1500° C. (themaximum combustion gas temperature) as a second combustion gastemperature at the inlet of the gas turbine. These characteristic curvesA and B are obtained by preliminary studies (gas turbine designing).

The gas turbine output learning circuit 201 firstly judges a conditionfor starting the learning by use of unillustrated learning-start judgingmeans. Specifically, the learning is started upon a judgment that avalue of the gas turbine output (the power generator output) actuallymeasured by the power meter PW is equal to or above the corrected value(the initial value) of the 1400° C.MW outputted from the multiplier 207.For example, when the output is raised by starting the gas turbine 1,the learning is started upon the judgment that the actual measurementvalue of the gas turbine output (the power generator output) is equal toor above this initial value of the corrected 1400° C.MW. Note that, theinitial value of the corrected 1400° C.MW at this time is determinedaccording to a correction coefficient obtained at the time of previousoperation of the gas turbine. Meanwhile, the learning is also startedupon a judgment that the actual measurement value of the gas turbineoutput (the power generator output) is equal to or above the initialvalue of the corrected 1400° C.MW in a case of dropping the gas turbineoutput once below a lower output than the corrected 1400° C.MW and thenraising the gas turbine output again. In this case as well, the initialvalue of the corrected 1400° C.MW at the time of raising the gas turbineoutput is determined according to the correction coefficient obtainedprior to once dropping the gas turbine output.

Note that, the judgment of the condition for starting the learning maybe carried out based on the characteristic curve A. Specifically, thelearning-start judging means may be configured to calculate the pressureratio (the cylinder pressure/the intake-air pressure) of the compressor4 by use of the actual measurement value of the intake-air pressuremeasured with the intake-air pressure gauge PX4 and the actualmeasurement value of the cylinder pressure measured with the cylinderpressure gauge PX5, to monitor this pressure ratio and the actualmeasurement value of the exhaust gas temperature with the exhaust gasthermometer Th, and to start the learning after a judgment that thepressure ratio and the exhaust gas temperature satisfy the relationrepresented by the characteristic curve A (such as a judgment that thepressure ratio and the exhaust gas temperature reach a point a on thecharacteristic curve A as shown in FIG. 20), or specifically after ajudgment that the combustion gas temperature at the inlet of the gasturbine rises and reaches the 1400° C.

Nevertheless, the learning is started in this embodiment not at thepoint when the judgment is made that the gas turbine output (the powergenerator output) is simply equal to or above the corrected 1400° C.MWor when the judgment is made that the combustion gas temperature TIT atthe inlet of the gas turbine reaches 1400° C. based on thecharacteristic curve A, but also after a lapse of a certain time periodsince variation in the gas turbine output (the power generator output)is eliminated (since variation in the load is eliminated). Specifically,the learning-start judging means is also configured to judge whether ornot variation in the measured value of the gas turbine output (the powergenerator output) with the power meter PW is absent or remains in apredetermined range for a certain period (such as 30 minutes). Hence,this learning-start judging means starts the learning after performingthe aforementioned judgment and also judging that the variation in thegas turbine output (the variation in the load) is absent or remains inthe predetermined range for the certain period.

When the learning is started, the logic in the gas turbine outputlearning circuit 201 shown in FIG. 19 starts functioning. First, a TITcomputing unit 202 starts computation of a current combustion gastemperature TIT at the inlet of the gas turbine. The TIT computing unit202 calculates a current pressure ratio (the cylinder pressure/theintake-air pressure) of the compressor 4 by use of the actualmeasurement value of the intake-air pressure with the intake-airpressure gauge PX4 and the actual measurement value of the cylinderpressure with the cylinder pressure gauge PX5. The TIT computing unit202 computes EXT1400 representing the exhaust gas temperature of the gasturbine body 2 corresponding to the pressure ratio as well astemperature controlled EXT by use of the following formulae (2) and (3),respectively:EXT1400=FX 1400 (pressure ratio)  (2)Temperature controlled EXT=FX 1500 (pressure ratio)  (3)

The formula (2) is the expression of the characteristic curve Aexpressing the exhaust gas temperature of the gas turbine body 2 in theform of a function of the pressure ratio of the compressor 4. Theformula (3) is the expression of the characteristic curve B expressingthe exhaust gas temperature of the gas turbine body 2 in the form ofanother function of the pressure ratio of the compressor 4. Accordingly,the formula (2) serves to compute the EXT1400 as a first exhaust gastemperature corresponding to the current pressure ratio measured by useof the intake-air pressure gauge PX4 and the cylinder pressure gauge PX5based on the characteristic curve A (means for computing the firstexhaust gas temperature). Meanwhile, the formula (3) serves to computethe temperature controlled EXT as a second exhaust gas temperaturecorresponding to the current pressure ratio based on the characteristiccurve B (means for computing the second exhaust gas temperature). Asshown in FIG. 20 as an example, assuming that the measured currentpressure ratio is PR1, the exhaust gas temperature EXT1 is computed byuse of the formula (2) as the EXT1400 corresponding to the currentpressure ratio PR1, while the exhaust gas temperature EXT2 is computedby use of the formula (3) as the temperature controlled EXTcorresponding to the current pressure ration PR1. Note that, the presentinvention is not limited only to application of the above-describedformulae. For example, it is also possible to compute the first exhaustgas temperature and the second exhaust gas temperature corresponding tothe current pressure ratio by means of linear interpolation(interpolating calculation) and the like by use of table data of thepressure ratios and the exhaust temperatures concerning thecharacteristic curves A and B.

Subsequently, the TIT computing unit 202 is means for computing a thirdcombustion gas temperature at the inlet of the gas turbine. The TITcomputing unit 202 computes the current combustion gas temperature TITat the inlet of the gas turbine as a third combustion gas temperature atthe inlet of the gas turbine corresponding to an exhaust gas temperatureEXT of a (current) actual measurement value. The calculation by the TITcomputing unit 202 is based on the temperature controlled EXT and theEXT1400 computed as described above, the value 1400° C. and the value1500° C. as the first and second combustion gas temperatures at theinlet of the gas turbine, and the actual measurement value of theexhaust gas temperature (such as an exhaust gas temperature EXT3 in FIG.20) measured with the exhaust gas thermometer Th, and uses the followingformula (4) representing a linear interpolation (interpolatingcalculation) formula. Note that, it is also possible to compute thecombustion gas temperature TIT at the inlet of the gas turbinecorresponding to the(current) actual measurement value of the exhaustgas temperature EXT by liner interpolation (interpolating calculation)in accordance with the following formula (5) which is virtuallyequivalent to the formula (4):

$\begin{matrix}{{TIT} = {1400 + {\frac{{EXT} - {{EXT}\; 1400}}{\begin{matrix}{{{temperature}\mspace{14mu}{controlled}}\mspace{11mu}} \\{{EXT} - {{EXT}\; 1400}}\end{matrix}} \times \left( {1500 - 1400} \right)}}} & (4) \\{{TIT} = {1500 - {\frac{\begin{matrix}{{temperature}\mspace{14mu}{controlled}} \\{\;{{EXT} - {EXT}}\;}\end{matrix}}{\begin{matrix}{{temperature}\mspace{14mu}{controlled}} \\{{EXT} - {{EXT}\; 1400}}\end{matrix}} \times \left( {1500 - 1400} \right)}}} & (5)\end{matrix}$

Next, an ideal MW computing unit 203 as means for computing a third gasturbine output computes ideal MW as a third gas turbine output (thepower generator output) corresponding to the combustion gas temperatureTIT at the inlet of the gas turbine computed by the TIT computing unit202 by use of the following formula (6) representing a linearinterpolation (interpolating calculation) formula. The calculation bythe ideal MW computing unit 203 is based on the combustion gastemperature TIT at the inlet of the gas turbine computed by the TITcomputing unit 202, the value 1400° C. and the value 1500° C. as thefirst and second combustion gas temperatures at the inlet of the gasturbine, the 1400° C.MW value as the first gas turbine output, and the1500° C.MW value (the temperature controlled MW) as the second gasturbine output. Note that, it is also possible to compute the ideal MWby liner interpolation (interpolating calculation) in accordance withthe following formula (7) which is virtually equivalent to the formula(6). The ideal MW computing unit 203 sets up a limit to prevent theideal MW from exceeding the temperature controlled MW for some reason:

$\begin{matrix}{{{{ideal}\mspace{14mu}{MW}} = {{1400{^\circ}\mspace{14mu}{C.\mspace{14mu}{MW}}} + {\frac{{TIT} - 1400}{1500 - 1400} \times \left( {{{temperature}\mspace{14mu}{controlled}\mspace{14mu}{MW}} - {1400{^\circ}\mspace{14mu}{C.\mspace{14mu}{MW}}}} \right)}}}\mspace{11mu}} & (6) \\{{{ideal}\mspace{14mu}{MW}} = {{{temperature}\mspace{14mu}{controlled}\mspace{14mu}{MW}} - {\frac{1500 - {TIT}}{1500 - 1400} \times \left( {{{temperature}\mspace{14mu}{controlled}\mspace{14mu}{MW}} - {1400{^\circ}\mspace{14mu}{C.\mspace{14mu}{MW}}}} \right)}}} & (7)\end{matrix}$

The 1500° C.MW value (the temperature controlled MW) is a valueoutputted from the multiplier 55 in FIG. 16, which is a value relevantto a certain intake-air temperature, a certain IGV aperture commandvalue, a certain turbine bypass ratio, and an atmospheric pressure ratioas described previously. The 1400° C.MW value is a value outputted froma multiplier 301 in FIG. 21, which is a value computed by use of thefollowing formula (8) in accordance with the computation method as inthe case of the 1500° C.MW value (the temperature controlled MW). Thatis, the 1400° C.MW value is also a value relevant to a certainintake-air temperature, a certain IGV aperture command value, a certainturbine bypass ratio, and the atmospheric pressure ratio:1400° C.MW=FX (intake-air temperature, IGV aperture, turbine bypassratio, atmospheric pressure ratio)  (8)

The following explanation will be based on computation logic shown inFIG. 21. First, a function generator 302 serving as the gas turbineoutput computing means computes the 1400° C.MW value as the first gasturbine output corresponding to the first combustion gas temperature atthe inlet of the gas turbine at 1400° C. The computation by the functiongenerator 302 is based on an actual measurement value of an intake-airtemperature measured by the intake-air thermometer Ta, the IGV aperturecommand value, and the turbine bypass ratio (a turbine bypass flowrate/an intake-air flow rate) calculated by dividing an actualmeasurement value of a turbine bypass flow rate measured with theturbine bypass flowmeter FX2 by an actual measurement value of anintake-air flow rate (which corresponds to a total amount of compressedair) measured with the intake-air flowmeter FX1 with the divider 53.That is, the 1400° C.MW value is calculated in consideration of the IGVaperture, the intake-air temperature, and the turbine bypass ratio. Thecomputation method for this 1400° C.MW value is the same as in the caseof the 1500° C.MW value described above. A divider 304 calculates theatmospheric pressure ratio (the intake-air pressure/the standardatmospheric pressure) by dividing the intake-air pressure (theatmospheric pressure) of the actual measurement value measured with theintake-air pressure gauge PX4 by the standard atmospheric pressure setup by a signal generator 305. The multiplier 301 calculates the 1400°C.MW value in consideration of the atmospheric pressure ratio bymultiplying the 1400° C.MW value calculated by the function generator302 by the atmospheric pressure ratio calculated by the divider 304.

Then, as shown in FIG. 19, the subtracter (the deviation operator) 63obtains a deviation between the ideal MW computed by the ideal MWcomputing unit 203 and the actual measurement value of the gas turbineoutput (the power generator output) measured with the power meter PW(the power generator output—the ideal MW). A function generator 211calculates a weighted coefficient corresponding to the CLCSO found byCLCSO computation logic based on a function between the CLCSO preset asshown in FIG. 22 and the weighted coefficient, and then outputs theweighted coefficient to a multiplier 212. In the example shown in FIG.22, the weighted coefficient is set equal to zero in a range of theCLCSO from 0 (%) to 80 (%), while the weighted coefficient is increasedfrom 0 to 1 in response to an increase in the CLCSO from 80 (%) to 100(%). However, the function is not limited only to the foregoing. It isalso possible, for example, to change the value of the CLCSO when theweighted coefficient starts to increase or to change the maximum valueof the weighted coefficient as appropriate.

The multiplier 212 performs weighting by multiplying the deviationoutputted from a subtracter (a deviation operator) 204 by the weightedcoefficient outputted from the function generator 211, and then outputsthe weighted deviation to a PI (proportion and integration) controller205 (means for weighting). Note that, the method of weighting thedeviation is not limited to the case based on the CLCSO. It is alsopossible to perform weighting based on the combustion gas temperatureTIT at the inlet of the gas turbine which is computed by the TITcomputing unit 202. In this case, the weighted coefficient, which issubject to an increase in response to an increase in the combustion gastemperature TIT at the inlet of the gas turbine, is calculated by thefunction generator 211 as in the case of the CLCSO. This weightedcoefficient is multiplied by the deviation with the multiplier 212.

The PI (proportion and integration) controller 205 calculates acorrection coefficient (ranging from 0 to 1) by subjecting thedeviation, which is obtained with the subtracter (the deviationoperator) 204 and weighted with the multiplier 212, to proportional andintegral operations. An initial value (i.e. an initial value of thecorrection coefficient) is set to 1 at the PI controller 205. When thegas turbine output (the power generator output) falls below thetemperature controlled MW due to deterioration in the performance of thegas turbine 1, an output (i.e. the correction coefficient) from the PIcontroller 205 is gradually decreased from 1 by subjecting the deviationbetween the gas turbine output (the power generator output) and thetemperature controlled MW at that point to the proportional and integraloperations. The gas turbine output learning circuit 201 stores thecorrection coefficient obtained (learned) by the PI controller 205. Whenthe gas turbine 1 stops, the gas turbine output learning circuit 201also stops learning. However, when the gas turbine 1 restarts to resumethe learning by the gas turbine output learning circuit 201, thecorrection coefficient learned by the gas turbine output learningcircuit 201 at the time of the previous operation of the gas turbine(i.e. the correction coefficient obtained immediately before stoppingthe learning) is defined as the initial value of the PI controller 205in the current operation. Note that, a proportional gain and an integraltime used in the PI controller 205 may be set to appropriate valuesdepending on tests or the like. Alternatively, the proportional gain maybe set equal to 0 (the PI controller 205 will execute only the integraloperation in this case).

A LOW limiter 206 limits a lower limit of the correction coefficient(ranging from 0 to 1) operated with the PI controller 205 equal to 0.95.Specifically, a learning range (the range of the correction coefficient)is set in the range from 0.95 to 1. As described previously, the reasonfor providing the limited range of the learning range (the range of thecorrection coefficient) is to consider an amount of presumable reductionin the power generator output (the gas turbine output) by normaldeterioration in the performance of the gas turbine 1 and to preventexcessive correction attributable to an abnormal drop in the output fromthe gas turbine 1.

A multiplier 207 multiplies the correction coefficient by the 1500° C.MWvalue (the temperature controlled MW) inputted from the multiplier 55shown in FIG. 16 to correct the 1500° C.MW value (the temperaturecontrolled MW), and outputs the result of multiplication to the ideal MWcomputing unit 203. A multiplier 208 multiplies the correctioncoefficient by the 1400° C.MW value inputted from the multiplier 301shown in FIG. 21 to correct the 1400° C.MW value, and outputs the resultof multiplication to the ideal MW computing unit 203. In other words,the subtracter (the deviation operator) 204, the PI controller 205, themultipliers 207 and 208, and so forth collectively constitute means forcorrecting the first gas turbine output and the second gas turbineoutput. Moreover, the ideal MW computing unit 203 computes the ideal MWby use of any of the above-described formulae (6) and (7) based on thecorrected 1500° C.MW value (the temperature controlled MW) and the 1400°C.MW value.

By repeating the above-described series of processes, the value of theideal MW computed by the ideal MW computing unit 203 eventually matcheswith the actual measurement value of the gas turbine output (the powergenerator output). Then, the 1500° C.MW (the temperature controlled MW)corrected with the correction coefficient by the multiplier 207 isoutputted to the subtracter 57 in the CLCSO computation logic shown inFIG. 16 for use in the calculation of the CLCSO. Note that, a lowervalue selector 209 selects a lower value out of the 1500° C.MW value(the temperature controlled MW) after correction by the multiplier 207and the rated power generator output (the gas turbine output) set up ina signal generator 210. Then, the lower value selector 209 outputs theselected value for use as control of the maximum output of the loadcontrol, LRCSO (a rate limitation on the CSO), the temperature control,and as a monitor display in an operating room, and so forth.

The corrected 1400° C.MW value to be outputted from the multiplier 208is used for determination of the condition for starting the learning asdescribed previously. Note that, it is also possible to apply thiscorrected 1400° C.MW value to some sort of control, a monitor display,and so forth.

Note that, this embodiment has described the case of applying the twocharacteristic curves A and B representing the combustion gastemperatures at the inlet of the gas turbine equal to 1400° C. and 1500°C., respectively. However, the present invention is not limited only tothis configuration. It is also possible to use other characteristiccurves representing different temperatures of the combustion gastemperatures at the inlet of the gas turbine instead of thecharacteristic curve A at 1400° C. and the characteristic curve B at1500° C. Alternatively, it is also possible to use other characteristiccurves at different temperatures in addition to the characteristiccurves A and B at the temperatures of 1400° C. and 1500° C.,respectively.

For example, as shown in FIG. 23, in addition to the characteristiccurves A and B at the temperatures of 1400° C. and 1500° C.,respectively, it is also possible to apply a characteristic curve Crepresenting a relation between the pressure ratio and the exhaust gastemperature when the combustion gas temperature at the inlet of the gasturbine is adjusted to 1300° C. as well as a characteristic curve Drepresenting a relation between the pressure ratio and the exhaust gastemperature when the combustion gas temperature at the inlet of the gasturbine is adjusted to 1200° C. In this case, methods to be used can besimilar to the methods of obtaining the combustion gas temperature TITat the inlet of the gas turbine and the ideal MW by performing the linerinterpolation (interpolating calculation) between the characteristiccurve B and the characteristic curve A as described above. By thismethods, it is also possible to calculate the combustion gas temperatureTIT at the inlet of the gas turbine and the ideal MW by performing theliner interpolation (interpolating calculation) between thecharacteristic curve A and the characteristic curve C or between thecharacteristic curve C and the characteristic curve D for example. Inthis way, it is possible to perform automatic correction of the gasturbine output even at a lower combustion gas temperature at the inletof the gas turbine. Note that, in a case of carrying out the linearinterpolation between the characteristic curve C and the characteristiccurve D, for example, the characteristic curve D constitutes the firstcharacteristic curve while the characteristic curve C constitutes thesecond characteristic curve. Moreover, the first combustion gastemperature at the inlet of the gas turbine becomes equal to 1200° C.while the second combustion gas temperature at the inlet of the gasturbine becomes equal to 1300° C. Furthermore, in this case, a 1200°C.MW value of the gas turbine output (the power generator output)corresponding to the temperature of 1200° C. represents the first gasturbine output while a 1300° C.MW value of the gas turbine output (thepower generator output) corresponding to the temperature of 1300° C.represents the second gas turbine output. The 1200° C.MW value and the1300° C.MW value can be calculated by a similar method to the case ofthe 1500° C.MW value as the value relevant to a certain intake-airtemperature, a certain IGV aperture command value, a certain turbinebypass ratio, and an atmospheric pressure ratio.

(Computation of Respective Valve Position Command Values Based on CLCSO)

Next, the processing for calculating the respective valve positioncommand values based on the CLCSO will be described.

First, computation logic of the combustor bypass valve position commandvalue (the BYCSO) will be described with reference to FIG. 24. Afunction generator 71 calculates the BYCSO corresponding to the CLCSOcalculated in accordance with the computation logic of the CLCSO basedon the preset function of the CLCSO and the combustor bypass valveposition command value (the BYCSO) as shown in FIG. 9.

Meanwhile, in this computation logic, this combustor bypass valveposition command value is subjected to correction based on the CLCSO andcorrection based on the intake-air temperature. Specifically, a functiongenerator 72 calculates a weight value of correction corresponding tothe CLCSO calculated in accordance with the computation logic of theCLCSO based on a function of the CLCSO and the weight of correction asshown in FIG. 25, which is set up in the preliminary studies (the gasturbine designing processes). A function generator 73 calculates acorrection efficient corresponding to the actual measurement value ofthe intake-air temperature based on a function of the intake-airtemperature and the correction coefficient as shown in FIG. 26, which isset up in the preliminary studies (the gas turbine designing processes).A multiplier 74 calculates an intake-air temperature correction amountby multiplying the weight value of correction based on the CLCSOcalculated with the function generator 72 by the correction coefficientbased on the intake-air temperature calculated with the functiongenerator 73. A subtracter 75 performs the intake-air temperaturecorrection of the BYCSO by subtracting the intake-air temperaturecorrection amount calculated with the multiplier 74 from the BYCSOcalculated with the function generator 71. That is, the functiongenerators 72 and 73, the multiplier 74, and the subtracter 75collectively constitute intake-air temperature correcting means.

The reason for performing the correction of the BYSCO based on theintake-air temperature is to achieve more appropriate combustion controlrelative to the variation in the intake-air temperature as compared tothe case of determining the BYSCO simply based on the CLCSO (thecombustion gas temperature at the inlet of the gas turbine). It isnoted, however, that the intake-air temperature correction amount may beset to a relatively large value with respect to the BYCSO withoutcausing any problems at the time of a low load (a low gas turbineoutput). However, a small change in the BYCSO may cause a large changein a combustion state at the time of a high load (a high gas turbineoutput). Accordingly, it is necessary to reduce the intake-airtemperature correction amount relative to the BYCSO. For this reason,the weight of correction is determined in response to the CLCSO (i.e.the gas turbine output) as described above, and the appropriateintake-air temperature correction amount for the BYCSO corresponding tothe CLCSO is determined by multiplying this weight value by thecorrection coefficient which is obtained from the intake-airtemperature.

Thereafter, the gas turbine combustion control device 41 controls thebypassing flow rate of the compressed air relative to the combustor 3 byregulating the aperture of the combustor bypass valve 8 based on theCLCSO calculated in accordance with this computation logic.

Next, computation logic (fuel flow rate command setting means) of apilot fuel flow rate command value (PLCSO) will be described withreference to FIG. 27. A function generator 81 calculates the pilot ratiocorresponding to the CLCSO calculated in accordance with the computationlogic of the CLCSO based on the function of the CLCSO and the pilotratio which is set up in advance as shown in FIG. 7.

Meanwhile, in this computation logic as well, this pilot ratio issubjected to correction based on the CLCSO and correction based on theintake-air temperature. Specifically, a function generator 82 calculatesa weight value of correction corresponding to the CLCSO calculated inaccordance with the computation logic of the CLCSO based on the functionof the CLCSO and the weight of correction as shown in FIG. 25, which isset up in the preliminary studies (the gas turbine designing processes).A function generator 83 calculates a correction efficient correspondingto the actual measurement value of the intake-air temperature based onthe function of the intake-air temperature and the correctioncoefficient as shown in FIG. 26, which is set up in the preliminarystudies (the gas turbine designing processes). A multiplier 84calculates an intake-air temperature correction amount by multiplyingthe weight value of correction based on the CLCSO calculated with thefunction generator 82 by the correction coefficient based on theintake-air temperature calculated with the function generator 83. Asubtracter 85 performs the intake-air temperature correction of thepilot ratio by subtracting the intake-air temperature correction amountcalculated with the multiplier 84 from the pilot ratio calculated withthe function generator 81. In other words, the function generators 82and 83, the multiplier 84, and the subtracter 85 collectively constitutethe intake-air temperature correcting means.

The reason for performing the correction of the pilot ratio based on theintake-air temperature is to achieve more appropriate combustion controlrelative to the variation in the intake-air temperature as compared tothe case of determining the pilot ratio simply based on the CLCSO (thecombustion gas temperature at the inlet of the gas turbine). It isnoted, however, that the intake-air temperature correction amount may beset to a relatively large value with respect to the pilot ratio withoutcausing any problems at the time of the low load (the low gas turbineoutput). However, a small change in the pilot ratio may cause a largechange in the combustion state at the time of the high load (i.e. thehigh gas turbine output). Accordingly, it is necessary to reduce theintake-air temperature correction amount relative to the pilot ratio.For this reason, the weight of correction is determined in response tothe CLCSO (i.e. the gas turbine output) as described above, and theappropriate intake-air temperature correction amount for the pilot ratiocorresponding to the CLCSO is determined by multiplying this weightvalue by the correction coefficient which is obtained from theintake-air temperature.

Thereafter, a multiplier 86 computes the PLCSO by multiplying a totalfuel flow rate command value (CSO) by the pilot ratio calculated withthe subtracter 85. The total fuel flow rate command value (CSO) is avalue proportional to a total fuel gas flow rate (a weight flow rate)G_(f) to be supplied to the combustor 3 (CSO x GO. Therefore, the PLCSOis a value proportional to the pilot gas fuel flow rate G_(fPL).

Note that, the total fuel flow rate command value (CSO) is set up basedon a relation between a power generator output command value, which isset up in advance in the preliminary studies (the gas turbine designingprocesses), and the CSO (i.e. the total fuel gas flow rate G_(f).Specifically, the gas turbine combustion control device 41 sets up thetotal fuel flow rate command value (CSO) based on the preset relation(the function) between the power generator output command value and theCSO by use of the power generator output command value set up by thecentral load dispatching center or the like. It is noted, however, thatthe gas turbine combustion control device 41 adjusts the total fuel flowrate command value (CSO) by use of an unillustrated control unit suchthat the actual measurement value of the power generator output matcheswith the power generator output command value. For example, the totalfuel flow rate command value (CSO) is adjusted such that the actualmeasurement value of the power generator output matches with the powergenerator output command value by subjecting a deviation between theactual measurement value of the power generator output and the powergenerator output command value to proportional and integral operationswith a PI controller.

Next, computation logic (the fuel flow rate command setting means) of atop hat fuel flow rate command value (THCSO) will be described withreference to FIG. 28. A function generator 91 calculates the top hatratio corresponding to the CLCSO calculated in accordance with thecomputation logic of the CLCSO based on the function of the CLCSO andthe top hat ratio which is set up in advance as shown in FIG. 8.

Meanwhile, in this computation logic as well, this top hat ratio issubjected to correction based on the CLCSO and correction based on theintake-air temperature. Specifically, a function generator 92 calculatesa weight value of correction corresponding to the CLCSO calculated inaccordance with the computation logic of the CLCSO based on the functionof the CLCSO and the weight of correction as shown in FIG. 25, which isset up in the preliminary studies (the gas turbine designing processes).A function generator 93 calculates a correction efficient correspondingto the actual measurement value of the intake-air temperature based onthe function of the intake-air temperature-and the correctioncoefficient as shown in FIG. 26, which is set up in the preliminarystudies (the gas turbine designing processes). A multiplier 94calculates an intake-air temperature correction amount by multiplyingthe weight value of correction based on the CLCSO calculated with thefunction generator 92 by the correction coefficient based on theintake-air temperature calculated with the function generator 93. Asubtracter 95 performs the intake-air temperature correction of the tophat ratio by subtracting the intake-air temperature correction amountcalculated with the multiplier 94 from the top hat ratio calculated withthe function generator 91. That is, the function generators 92 and 93,the multiplier 94, and the subtracter 95 collectively constitute theintake-air temperature correcting means.

The reason for performing the correction of the top hat ratio based onthe intake-air temperature is to achieve more appropriate combustioncontrol relative to the variation in the intake-air temperature ascompared to the case of determining the top hat ratio simply based onthe CLCSO (the combustion gas temperature at the inlet of the gasturbine). It is noted, however, that the intake-air temperaturecorrection amount may be set to a relatively large value with respect tothe top hat ratio without causing any problems at the time of the lowload (the low gas turbine output). However, a small change in the tophat ratio may cause a large change in the combustion state at the timeof the high load (the high gas turbine output). Accordingly, it isnecessary to reduce the intake-air temperature correction amountrelative to the top hat ratio. For this reason, the weight of correctionis determined in response to the CLCSO (i.e. the gas turbine output) asdescribed above, and the appropriate intake-air temperature correctionamount for the top hat ratio corresponding to the CLCSO is determined bymultiplying this weight value by the correction coefficient which isobtained from the intake-air temperature. Although details will bedescribed later, the main ratio is also computed based on the pilotratio and the top hat ratio, and is therefore subjected to intake-airtemperature correction.

A multiplier 96 computes the THCSO by multiplying the CSO by the top hatratio calculated with the subtracter 95. The THCSO is proportional tothe top hat gas fuel flow rate (a weight flow rate) G_(fTH).

Next, computation logic of the respective flow rate control valveposition command values will be described with reference to FIG. 29.

First, the computation logic of the pilot fuel flow rate control valvecommand value will be described. A function generator 101 computes thevalue of the pilot fuel flow rate G_(fPL) corresponding to the PLCSOcalculated with the multiplier 86 in accordance with the computationlogic of the PLCSO as described above based on a function of the PLCSOand the pilot gas flow rate G_(fPL) as shown in FIG. 30 as an example(fuel flow rate setting means). In other words, the PLCSO is convertedinto a weight flow rate Q. The function of (or a proportional relationbetween) the PLCSO and the pilot fuel gas flow rate G_(fPL) is set up inadvance in the preliminary studies (the gas turbine designingprocesses).

Subsequently, the Cv value of the pilot fuel flow rate control valve 19is computed based on the following formula (9) representing a Cv valuecalculation formula:

$\begin{matrix}\left. \begin{matrix}{{Cv} = {\frac{aG}{289}\sqrt{\frac{\gamma\left( {t + 273} \right)}{P_{1}^{2} - P_{2}^{2}}}}} \\{a = {\frac{1}{\gamma_{N}} \cdot \frac{273 + 15.6}{273}}}\end{matrix} \right\} & (9)\end{matrix}$

In the formula (9), reference code t denotes the temperature of thepilot fuel gas flowing on the pilot fuel flow rate control valve 19. Avalue measured with the fuel gas thermometer Tf is applied to this pilotfuel gas temperature. Reference code γ denotes a gas density ratiorelative to the air, which is a preset value. Reference code G denotesthe pilot fuel gas flow rate (the weight flow rate) flowing on the pilotfuel flow rate control valve 19. The pilot fuel gas flow rate G_(fPL)calculated with the function generator 101 is applied to this pilot fuelgas flow rate. Reference code a denotes a coefficient used forconverting the pilot fuel gas flow rate G into a volume flow rate (m³/h)at 15.6° C. and at 1 ata. The coefficient a is a preset value. Referencecode γN denotes gas density in a normal state.

Moreover, in the formula (9), reference code P₂ denotes a back pressure(a pressure on a downstream side) of the pilot fuel flow rate controlvalve 19. A measurement value or a corrected value (to be describedlater in detail) of the pilot manifold pressure gauge PX2 is applied tothis back pressure. Reference code P₁ denotes a front pressure (apressure on an upstream side) of the pilot fuel flow rate control valve19. A value obtained by adding a front-to-back differential pressure ofthe pilot fuel flow rate control valve 19 (such as 4 kg/cm²) to themeasurement value of the pilot manifold pressure gauge PX2 is applied tothis front pressure. This front-to-back differential pressure isadjusted to be a constant value by use of the pilot fuel pressurecontrol valve 18. It is to be noted, however, that the present inventionwill not be limited only to this configuration. It is possible to applya measurement value of the pilot fuel differential pressure gauge PDX2to the front-to-back differential pressure. Alternatively, when thefront pressure of the pilot fuel flow rate control valve 19 is measuredwith a pressure gauge, it is possible to apply the measurement value ofthat pressure gauge to the P₁ value.

In terms of explanation based on the computation logic, a functiongenerator 102 performs a calculation in accordance with the followingformula (10) based on the pilot manifold pressure (used as the backpressure P₂), which is either the actual measurement value or thecorrected value using manifold pressure correction logic 130 (to bedescribed later in detail) functioning as pressure correcting means:

$\begin{matrix}\frac{1}{\sqrt{\left( {4 + P_{2}} \right)^{2} - P_{2}^{2}}} & (10)\end{matrix}$

A function generator 103 performs a calculation in accordance with thefollowing formula (11) based on the fuel gas temperature (used as thepilot fuel gas temperature t), which is either an actual measurementvalue inputted by use of fuel gas temperature correction logic 120 (tobe described later in detail) functioning as fuel temperature correctingmeans, or a constant value:

$\begin{matrix}\frac{a\sqrt{\gamma\left( {t + 273} \right)}}{289} & (11)\end{matrix}$

A multiplier 104 multiplies the pilot fuel gas flow rate G_(fPL) (usedas the pilot fuel gas flow rate G) calculated with the functiongenerator 101 by a result of calculation with the function generator102, and then by a result of calculation with the function generator103. In this way, the calculation of the above-described formula (9) iscompleted and the Cv value of the pilot fuel flow rate control valve 19is obtained (Cv value setting means). A function generator 105calculates an aperture of the pilot fuel flow rate control valvecorresponding to the Cv value of the pilot fuel flow rate control valve19 calculated with the multiplier 104 based on a function of theaperture of the pilot fuel flow rate control valve and the Cv value asshown in FIG. 31, which is set up in advance in the preliminary studies(specifications of the control valve). Then, the aperture of the pilotfuel flow rate control valve is outputted as the pilot fuel flow ratecontrol valve position command value (fuel flow rate control valveposition command setting means).

Thereafter, the gas turbine combustion control device 41 controls thepilot fuel gas flow rate by regulating the aperture of the pilot fuelflow rate control valve 19 based on the pilot fuel flow rate controlvalve position command value calculated in accordance with thiscomputation logic.

Now, the computation logic of the top hat fuel flow rate control valvecommand value will be described. A function generator 106 computes thevalue of the top hat fuel gas flow rate G_(fTH) corresponding to theTHCSO calculated with the multiplier 96 in accordance with thecomputation logic of the THCSO as described above based on a function ofthe THCSO and the top hat fuel gas flow rate G_(fTH) as shown in FIG. 32as an example (the fuel flow rate setting means). In other words, theTHCSO is converted into a weight flow rate Q. The function of (or aproportional relation between) the THCSO and the top hat fuel gas flowrate G_(fTH) is set up in advance in the preliminary studies (the gasturbine designing processes).

Subsequently, the Cv value of the top hat fuel flow rate control valve21 is computed based on the above-described formula (9) (the Cv valuecalculation formula). In terms of the formula (9) in this case, however,it is to be noted that the reference code t denotes the temperature ofthe top hat fuel gas flowing on the top hat fuel flow rate control valve21. The value measured with the fuel gas thermometer Tf is applied tothis top hat fuel gas temperature. The reference code G denotes the tophat fuel gas flow rate (the weight flow rate) flowing on the top hatfuel flow rate control valve 21. The top hat fuel gas flow rate G_(fTH)calculated with the function generator 106 is applied to this top hatfuel gas flow rate. The reference code a denotes a coefficient used forconverting the top hat fuel gas flow rate G into a volume flow rate(m³/h) at 15.6° C. and at 1 ata.

Moreover, in the formula (9), the reference code P₂ denotes a backpressure (a pressure on a downstream side) of the top hat fuel flow ratecontrol valve 21. A measurement value or a corrected value (to bedescribed later in detail) of the top hat manifold pressure gauge PX3 isapplied to this back pressure. The reference code P₁ denotes a frontpressure (a pressure on an upstream side) of the top hat fuel flow ratecontrol valve 21. A value obtained by adding a front-to-backdifferential pressure of the top hat fuel flow rate control valve 21(such as 4 kg/cm²) to the measurement value of the top hat manifoldpressure gauge PX3 is applied to this front pressure. This front-to-backdifferential pressure is adjusted to be a constant value by use of thetop hat fuel pressure control valve 20. It is to be noted, however, thatthe present invention will not be limited only to this configuration. Itis possible to apply a measurement value of the top hat fueldifferential pressure gauge PDX3 to the differential pressure.Alternatively, when the front pressure of the top hat fuel flow ratecontrol valve. 21 is measured with a pressure gauge, it is possible toapply the measurement value of that pressure gauge to the P₁ value.

In terms of explanation based on the computation logic, a functiongenerator 107 performs the calculation in accordance with theabove-described formula (10) based on the top hat manifold pressure(used as the back pressure P₂), which is either the actual measurementvalue or the corrected value using manifold pressure correction logic140 (to be described later in detail) functioning as the pressurecorrecting means. The function generator 103 performs the calculation inaccordance with the above-described formula (11) based on an actualmeasurement value of the fuel gas temperature (used as the top hat fuelgas temperature t) (as similar to the case of calculating the Cv valueof the pilot fuel flow rate control valve 19).

A multiplier 109 multiplies the top hat fuel gas flow rate G_(fTH) (usedas the top hat fuel gas flow rate G) calculated with the functiongenerator 106 by a result of calculation with the function generator107, and then by a result of calculation with the function generator103. In this way, the calculation of the above-described formula (9) iscompleted and the Cv value of the top hat fuel flow rate control valve21 is obtained (the Cv value setting means). A function generator 110calculates an aperture of the top hat fuel flow rate control valvecorresponding to the Cv value of the top hat fuel flow rate controlvalve 21 calculated with the multiplier 109 based on the function of theaperture of the top hat fuel flow rate control valve and the Cv value asshown in FIG. 31, which is set up in advance in the preliminary studies(the specifications of the control valve). Then, the aperture of the tophat fuel flow rate control valve is outputted as the top hat fuel flowrate control valve position command value (the fuel flow rate controlvalve position command setting means).

Thereafter, the gas turbine combustion control device 41 controls thetop hat fuel gas flow rate by regulating the aperture of the top hatfuel flow rate control valve 21 based on the top hat fuel flow ratecontrol valve position command value calculated in accordance with thiscomputation logic.

Now, the computation logic of the main fuel flow rate control valvecommand value will be described. An adder 111 adds the PLCSO calculatedwith the multiplier 86 of the computation logic of the PLCSO to theTHCSO calculated with the multiplier 96 of the computation logic of theTHCSO (PLCSO+THCSO). A subtracter 112 subtracts a result of additionwith the adder 111 from the CSO (MACSO=CSO−PLCSO−THCSO) and therebycomputes a main fuel flow rate command value (MACSO) (the fuel flow ratecommand setting means). The MACSO is proportional to the main fuel gasflow rate G_(fMA).

A function generator 113 computes the value of the main fuel gas flowrate GI corresponding to the MACSO calculated with the subtracter 112based on a function of the MACSO and the main fuel gas flow rate G_(fMA)as shown in FIG. 33 as an example (the fuel flow rate setting means). Inother words, the MACSO is converted into a weight flow rate Q. Thefunction of (or a proportional relation between) the MACSO and the mainfuel gas flow rate G_(fMA) is set up in advance in the preliminarystudies (the gas turbine designing processes).

Subsequently, the Cv value of the main fuel flow rate control valve 17is computed based on the above-described formula (9) (the Cv valuecalculation formula). In terms of the formula (9) in this case, however,it is to be noted that the reference code t denotes the temperature ofthe main fuel gas flowing on the main fuel flow rate control valve 17.The value measured with the fuel gas thermometer Tf is applied to thismain fuel gas temperature. The reference code G denotes the main fuelgas flow rate (the weight flow rate) flowing on the main fuel flow ratecontrol valve 17. The main fuel gas flow rate G_(fMA) calculated withthe function generator 113 is applied to this main fuel gas flow rate.The reference code a denotes a coefficient used for converting the mainfuel gas flow rate G into a volume flow rate (m³/h) at 15.6° C. and at 1ata.

Moreover, in the formula (9), the reference code P₂ denotes a backpressure (a pressure on a downstream side) of the main fuel flow ratecontrol valve 17. A measurement value or a corrected value (to bedescribed later in detail) of the main manifold pressure gauge PX1 isapplied to this back pressure. The reference code P₁ denotes a frontpressure (a pressure on an upstream side) of the main fuel flow ratecontrol valve 17. A value obtained by adding a front-to-backdifferential pressure of the main fuel flow rate control valve 17 (suchas 4 kg/cm²) to the measurement value of the main manifold pressuregauge PX1 is applied to this front pressure. This front-to-backdifferential pressure is adjusted to be a constant value by use of themain fuel pressure control valve 16. It is to be noted, however, thatthe present invention will not be limited only to this configuration. Itis possible to apply a measurement value of the main fuel differentialpressure gauge PDX1 to the front-to-back differential pressure.Alternatively, when the front pressure of the main fuel flow ratecontrol valve 17 is measured with a pressure gauge, it is possible toapply the measurement value of that pressure gauge to the P₁ value.

In terms of explanation based on the computation logic, a functiongenerator 114 performs the calculation in accordance with theabove-described formula (10) based on the main manifold pressure (usedas the back pressure P₂), which is either the actual measurement valueor the corrected value using manifold pressure correction logic 150 (tobe described later in detail) functioning as the pressure correctingmeans. The function generator 103 performs the calculation in accordancewith the above-described formula (11) based on an actual measurementvalue of the fuel gas temperature (used as the main fuel gas temperaturet) (as similar to the case of calculating the Cv value of the pilot fuelflow rate control valve 19).

A multiplier 115 multiplies the main fuel gas flow rate G_(fMA) (used asthe main fuel gas flow rate G) calculated with the function generator113 by a result of calculation with the function generator 114, and thenby a result of calculation with the function generator 103. In this way,the calculation of the above-described formula (9) is completed and theCv value of the main fuel flow rate control valve 17 is obtained (the Cvvalue setting means). A function generator 116 calculates an aperture ofthe main fuel flow rate control valve corresponding to the Cv value ofthe main fuel flow rate control valve 17 calculated with the multiplier115 based on the function of the aperture of the main fuel flow ratecontrol valve and the Cv value as shown in FIG. 31, which is set up inadvance in the preliminary studies (the specifications of the controlvalve). Then, the aperture of the main fuel flow rate control valve isoutputted as the main fuel flow rate control valve position commandvalue (the fuel flow rate control valve position command setting means).

Thereafter, the gas turbine combustion control device 41 controls themain fuel gas flow rate by regulating the aperture of the main fuel flowrate control valve 17 based on the main fuel flow rate control valveposition command value calculated in accordance with this computationlogic.

Next, the fuel gas temperature correction logic and the manifoldpressure correction logic functioning as correction logic in the eventof anomalies of instruments will be described.

First, the fuel gas temperature correction logic will be described withreference to FIG. 34. The actual measurement value of the fuel gastemperature is inputted to a lag time setter 122 and a switch 123,respectively. It is noted, however, that when the multiple fuel gasthermometers Tf are installed (when the gas thermometers Tf aremultiplexed), the actual measurement value of the fuel gas temperatureis inputted via a lower value selector 121. The lower value selector 121selects and outputs the lowest value out of the values measured by themultiple fuel gas thermometers Tf (two thermometers in the illustratedexample).

The lag time setter 122 outputs the actual measurement value of the fuelgas temperature, which is inputted from the fuel gas thermometer Tf,after passage of predetermined lag time L since the actual measurementvalue is inputted. When an instrument anomaly signal is not inputtedfrom an instrument anomaly detection device (not shown) for detecting ananomaly of the fuel gas thermometer Tf attributable to disconnection orthe like, the switch 123 usually outputs the actual measurement value ofthe fuel gas temperature which is inputted from the fuel gas thermometerTf (inputted directly without interposing the lag time setter 122). Onthe contrary, if the instrument anomaly signal is inputted, the switch123 changes a route to the lag time setter 122, and outputs the inputtedvalue through this lag time setter 122. Note that, the output value fromthe lag time setter 122 may vary depending on the input value even afterthis switching operation attributable to the instrument anomaly signal.However, the switch 123 holds and continues to output the value of thefuel gas temperature inputted from the lag time setter 122 at the pointof the switching operation attributable to the instrument anomalysignal. In other words, after the switching operation attributable tothe instrument anomaly signal, the constant value of the fuel gastemperature is outputted from the switch 123.

The output from the switch 123 is inputted to a primary delay operator124 functioning as a first primary delay operator and to a primary delayoperator 125 functioning as a second primary delay operator,respectively. A primary delay time constant set in the primary delayoperator 125 for a rate decrease is smaller than a primary delay timeconstant set in the primary delay operator 124 for a rate increase. Theprimary delay operator 124 performs a primary delay calculation in termsof the fuel gas temperature inputted from the switch 123, and theprimary delay operator 125 also performs a primary delay calculation interms of the fuel gas temperature inputted from the switch 123. Then,the lower value selector 126 selects and outputs a smaller value out ofa result of operation by the primary delay operator 124 and a result ofoperation by the primary delay operator 125.

When a rated speed (rated revolution) achievement signal is not inputtedfrom an unillustrated gas turbine revolution detection device (that is,when the gas turbine 1 is accelerating), a rating switch 127 selects theconstant value of the fuel gas temperature set in a signal generator 128and outputs the constant value to the function generator 103 of the flowrate control valve position command value computation logic shown inFIG. 29. On the contrary, when the rated speed achievement signal isinputted, the rating switch 127 selects the output of the lower valueselector 126 and outputs that value to the function generator 103 of thesame computation logic. Here, in order to prevent a rapid change in thefuel gas temperature, the rating switch 127 increases or decreases theoutput at a given rate when switching the selected signal from theoutput of the signal generator 128 to the output of the lower valueselector 126 or vice versa.

Next, the manifold pressure correction logic will be described. Asdescribed previously, the correction of the manifold pressure takesplace in terms of the pilot manifold pressure, the top hat manifoldpressure, and the main manifold pressure (see the manifold pressurecorrection logic 130, 140 or 150 in FIG. 29). Nevertheless, the schemesof the manifold pressure correction logic 130, 140, and 150 are similar.Accordingly, individual illustration and explanation will be omittedherein, and the contents of processing in these schemes of the manifoldpressure correction logic 130, 140, and 150 will be described alltogether based on FIG. 35 to FIG. 38.

As shown in FIG. 35, when an instrument anomaly signal is not inputtedfrom an instrument anomaly detection device (not shown) for detecting ananomaly of the pilot manifold pressure gauge PX2 (or any of the top hatmanifold pressure gauge PX3 and the main manifold fuel differentialpressure gauge PDX1) attributable to disconnection or the like, a switch161 usually outputs the actual measurement value of pilot manifoldpressure (or any of the top hat manifold pressure and the main manifoldpressure) inputted from the pilot manifold pressure gauge PX2 (or any ofthe top hat manifold pressure gauge PX3 and the main manifolddifferential pressure gauge PDX1) to a change rate setter 162. On thecontrary, if the instrument anomaly signal is inputted, the switch 161changes a route to manifold pressure computation logic 163 functioningas pressure computing means, and outputs a calculated value of the pilotmanifold pressure (or any of the top hat manifold pressure and the mainmanifold pressure) inputted from this manifold pressure computationlogic 163 to the change rate setter 162.

The change rate setter 162 sets up the change rate based on a functionof the power generator output (the gas turbine output) and the changerate as shown in FIG. 36 as an example, which is set up in advance inthe preliminary studies (the gas turbine designing processes) as well asbased on an actual measurement value or a command value of the powergenerator output (the gas turbine output). Then, based on that changerate, the change rate setter 162 restricts the rate of change in termsof either the actual measurement value or the calculated value of thepilot manifold pressure (or any of the top hat manifold pressure and themain manifold pressure) to be inputted from the switch 161 and outputtedto the function generator 102 (or any of the function generator 107 andthe function generator 114) of the flow rate control valve positioncommand value computation logic shown in FIG. 29.

In the case of an anomaly other than a choke, the manifold pressurecomputation logic 163 calculates the pilot manifold pressure (or any ofthe top hat manifold pressure and the main manifold pressure) based onthe following formula (13) obtained by modifying the following formula(12) that represents the Cv value calculation formula for an anomalyother than a choke. Meanwhile, in the case of an anomaly attributable toa choke, the manifold pressure computation logic 163 calculates thepilot manifold pressure (or any of the top hat manifold pressure and themain manifold pressure) based on the following formula (15) obtained bymodifying the following formula (14) that represents the Cv valuecalculation formula for an anomaly attributable to a choke.

$\begin{matrix}\left. \begin{matrix}{{Cv} = {\frac{aG}{289}\sqrt{\frac{\gamma\left( {t + 273} \right)}{P_{2}^{2} - P_{3}^{2}}}}} \\{a = {\frac{1}{\gamma_{N}} \cdot \frac{273 + 15.6}{273}}}\end{matrix} \right\} & (12) \\\left. \begin{matrix}{P_{2} = \sqrt{\left( {\frac{aG}{289{Cv}} \cdot \sqrt{\gamma\left( {t + 273} \right)}} \right)^{2} + P_{3}^{2}}} \\{a = {\frac{1}{\gamma_{N}} \cdot \frac{273 + 15.6}{273}}}\end{matrix} \right\} & (13) \\\left. \begin{matrix}{{Cv} = \frac{{aG}\sqrt{\gamma\left( {t + 273} \right)}}{250P_{2}}} \\{a = {\frac{1}{\gamma_{N}} \cdot \frac{273 + 15.6}{273}}}\end{matrix} \right\} & (14) \\\left. \begin{matrix}{P_{2} = {\frac{aG}{250{Cv}} \cdot \sqrt{\gamma\left( {t + 273} \right)}}} \\{a = {\frac{1}{\gamma_{N}} \cdot \frac{273 + 15.6}{273}}}\end{matrix} \right\} & (15)\end{matrix}$

In the formula (12) and the formula (13), reference code Cv denotes theCv value of the pilot nozzle 25 (or any of the top hat nozzle 27 and themain nozzle 26). A preset constant value or a correction value correctedby a learning circuit (to be described later in detail) is applied tothis Cv value. Reference code t denotes the temperature of the pilotfuel gas (or any of the top hat fuel gas and the main fuel gas) ejectedfrom the pilot nozzle 25 (or any of the top hat nozzle 27 and the mainnozzle 26). A value measured with the fuel gas thermometer Tf is appliedto any of these fuel gas temperatures. Reference code γ denotes a gasdensity ratio relative to the air, which is a preset value.

Reference code G denotes the pilot fuel gas flow rate (the weight flowrate) (or any of the top hat fuel gas flow rate (the weight flow rate)and the main fuel gas flow rate (the weight flow rate)) ejected from thepilot nozzle 25 (or any of the top hat nozzle 27 and the main nozzle26). The pilot fuel gas flow rate G_(fPL) calculated with the functiongenerator 101 (or any of the top hat fuel gas flow rate G_(fTH)calculated with the function generator 106 and the main fuel gas flowrate G_(fMA) calculated with the function generator 113) of the flowrate control valve position command value computation logic in FIG. 29is applied to any of these fuel gas flow rates.

Note that, the pilot fuel gas flow rate G_(fPL) (or any of the top hatfuel gas flow rate G_(fTH) and the main fuel gas flow rate G_(fMA))represents the total pilot fuel gas flow rate G_(fPL) (or any of thetotal top hat fuel gas flow rate G_(fTH) and the total main fuel gasflow rate G_(fMA)). A result of distribution of the relevant fuel gasflow rate to the respective pilot nozzles 25 (or any of the respectivetop hat nozzles 27 and the respective main nozzles 26) is equivalent tothe fuel gas flow rate of each of the pilot nozzles 25 (or any of eachof the top hat nozzles 27 and each of the main nozzles 26). Therefore, avalue obtained by dividing the pilot fuel gas flow rate G_(fPL) (or anyof the top hat fuel gas flow rate G_(fTH) and the main fuel gas flowrate G_(fMA)) by the number of the pilot nozzles 25 (or any of the tophat nozzles 27 and the main nozzles 26) is used as the pilot fuel gasflow rate (or any of the top hat fuel gas flow rate and the main fuelgas flow rate) G of each of the pilot nozzles 25 (or any of each of thetop hat nozzles 27 and each of the main nozzles 26). Reference code adenotes a coefficient used for converting any of these fuel gas flowrates G into a volume flow rate (m³/h) at 15.6° C. and at 1 ata. Thecoefficient a is a preset value. Reference code γN denotes gas densityin a normal state.

Moreover, in the formula (12) and formula (13), reference code P₃denotes a back pressure (a pressure on a downstream side) of the pilotnozzle 25 (or any of the top hat nozzle 27 and the main nozzle 26). Ameasurement value of the cylinder pressure gauge PX5 is applied to thisback pressure (see FIG. 3). Reference code P₂ denotes a front pressure(a pressure on an upstream side) of the pilot nozzle 25 (or any of thetop hat nozzle 27 and the main nozzle 26), i.e. the pilot manifoldpressure (or any of the top hat manifold pressure and the main manifoldpressure).

In terms of explanation based on-computation logic shown in FIG. 37, amultiplier 164 multiplies the Cv value (the constant value) of the pilotnozzle 25 (or any of the top hat nozzle 27 and the main nozzle 26)preset in a signal generator 165 by a correction coefficient (to bedescribed later in detail) calculated by the learning circuit 166 aslearning means. A function generator 167 performs a calculation inaccordance with the following formula (16) based on the actualmeasurement value of the fuel gas temperature (any one of the pilot fuelgas temperature t, the top hat fuel gas temperature t, and the main fuelgas temperature t). A multiplier 168 multiplies the pilot fuel gas flowrate G (or any of the top hat fuel gas flow rate G and the main fuel gasflow rate G), which is obtained based on the pilot fuel gas flow rateG_(fPL) calculated with the function generator 101 (or any of the tophat fuel gas flow rate G_(fTH) calculated with the function generator106 and the main fuel gas flow rate G_(fMA) calculated with the functiongenerator 113) of the flow rate control valve position command valuecomputation logic in FIG. 29, by a result of calculation with thefunction generator 164. A divider 169 divides a result of multiplicationwith the multiplier 168 by a result of multiplication with themultiplier 164.√{square root over (γ(t+273))}  (16)

A multiplier 171 multiplies a result of division with the divider 169 bya value obtained by the following formula (17) which is set in a signalgenerator 170:

$\begin{matrix}{\frac{1}{\gamma_{N}} \cdot \frac{273 + 15.6}{273} \cdot \frac{1}{289}} & (17)\end{matrix}$

A multiplier 172 multiplies a result of multiplication with themultiplier 171 by the same value (i.e., the multiplier 172 calculates asquare of the result of multiplication with the multiplier 171). Anadder 173 adds the value (1.0332) set in a signal generator 174 to theactual measurement value of the cylinder pressure (used as the backpressure P₂ of the pilot nozzle, the top hat nozzle or the main nozzle)and forms the cylinder pressure being the measurement value of thecylinder pressure gauge PX5 into an absolute pressure. A multiplier 175multiplies a result of addition with the adder 173 by the same value(i.e., the multiplier 175 calculates a square of the cylinder pressureP₂). An adder 176 adds a result of multiplication with the multiplier172 to a result of multiplication with the multiplier 175. That is, acalculation in accordance with the following formula (18) is completedby the time of the processing with this adder 176. Then, a rooter 177calculates a root of a result of addition with the adder 176. That is,the calculation in accordance with the above-described formula (13) iscompleted by the time of the processing with this rooter 177. In thisway, a calculated value P₂ in terms of the pilot manifold pressure (orany of the top hat manifold pressure and the main manifold pressure) inthe case of an anomaly other than a choke is obtained.

$\begin{matrix}{\left( {\frac{aG}{289{Cv}} \cdot \sqrt{\gamma\left( {t + 273} \right)}} \right)^{2} + P_{3}^{2}} & (18)\end{matrix}$

Meanwhile, a multiplier 179 multiplies the result of division by theabove-described divider 169 by a value obtained by the following formula(19) which is set in a signal generator 178. That is, the calculation inaccordance with the above-described formula (15) is completed by thetime of the processing with this multiplier 179. In this way, thecalculated value P₂ in terms of the pilot manifold pressure (or any ofthe top hat manifold pressure and the main manifold pressure) in thecase of an anomaly attributable to a choke is obtained.

$\begin{matrix}{\frac{1}{\gamma_{N}} \cdot \frac{273 + 15.6}{273} \cdot \frac{1}{250}} & (19)\end{matrix}$

A choke identifier 180 compares the pilot manifold pressure (or any ofthe top hat manifold pressure and the main manifold pressure) P₂ that isthe output of the rooter 177 with the cylinder pressure (the backpressure of any of the pilot nozzle, the top hat nozzle, and the mainnozzle) P₃ that is the output of the adder 173, and identifies a chokewhen the condition as defined in the following formula (20) issatisfied:

$\begin{matrix}{P_{3} \leq {\frac{1}{2}P_{2}}} & (20)\end{matrix}$

A switch 181 selects the output value of the multiplier 179 when thechoke identifier 180 identifies the choke, and outputs that value to theswitch 161 in FIG. 35 as the calculated pilot manifold pressure (or anyof the calculated top hat manifold pressure and the calculated mainmanifold pressure) P₂. On the contrary, the switch 181 selects theoutput value of the rooter 177 when the choke identifier 180 does notidentify the choke, (in the case of an anomaly other than a choke), andoutputs that value to the switch 161 in FIG. 35 as the calculated pilotmanifold pressure (or any of the calculated top hat manifold pressureand the calculated main manifold pressure) P₂.

Next, the learning circuit 166 will be described with reference to FIG.38. As similar to the case of the learning circuit 62, the learningcircuit 166 firstly judges whether or not the combustion gas temperatureTIT reaches the maximum combustion gas temperature (1500° C.) beforestarting to learn the nozzle Cv value. Specifically, when the combustiongas temperature TIT at the inlet of the gas turbine is equal to themaximum combustion gas temperature (1500° C.), there is the relationbetween the pressure ratio of the compressor 4 (the ratio between thepressure on the inlet side and the pressure on the outlet side of thecompressor 4) and the exhaust gas temperature as shown in FIG. 18.Therefore, the learning circuit 166 monitors the pressure ratio (thecylinder pressure/the intake-air pressure) of the compressor 4 obtainedfrom the actual measurement value of the intake-air pressure and theactual measurement value of the cylinder pressure as well as the actualmeasurement value of the exhaust gas temperature. Moreover, the learningcircuit 62 judges that the combustion gas temperature TIT at the inletof the gas turbine reaches the maximum combustion gas temperature (1500°C.) when the pressure ratio and the exhaust gas temperature satisfy therelation shown in FIG. 18, and then starts learning. It is to be noted,however, that the present invention will not be limited only to thisconfiguration. For example, it is also possible to start learning beforethe combustion gas temperature TIT at the inlet of the gas turbinereaches the maximum combustion gas temperature (1500° C.).

When the learning circuit 166 starts learning, a subtracter (a deviationoperator) 182 firstly calculates a deviation between the pilot manifoldpressure (or any of the top hat manifold pressure and the main manifoldpressure) P₂ calculated in accordance with the manifold pressurecorrection logic 163 and the pilot manifold pressure (or any of the tophat manifold pressure and the main manifold pressure) measured with themain manifold pressure gauge PX2 (or any of the top hat manifoldpressure gauge PX3 and the main manifold pressure gauge PX1).

Thereafter, a PI controller 183 performs proportional and integraloperations based on the deviation to calculate the correctioncoefficient in a range from 0 to 1. This correction efficient isoutputted to the multiplier 164 of the manifold pressure correctionlogic 163 in FIG. 37 and is then multiplied by the nozzle Cv value (thefixed value) set in the signal generator 165. In this way, by correctingthe nozzle Cv value so as to eliminate the deviation between thecalculated value of the pilot manifold pressure (or any of the top hatmanifold pressure and the main manifold pressure) P₂ and the actualmeasurement value of the pilot manifold pressure (or any of the top hatmanifold pressure and the main manifold pressure). Accordingly it ispossible to obtain a more accurate nozzle Cv value.

(Operation Effects)

As described above, according to the gas turbine combustion controldevice 41 of this embodiment, the 700° C.MW value and the 1500° C.MWvalue are calculated based on the IGV aperture, the intake-airtemperature, and the atmospheric pressure ratio. Then, based on thesevalues and on the actual measurement value of the power generator output(the gas turbine output), the CLCSO to render the combustion gastemperature at the inlet of the gas turbine dimensionless is computed bylinear interpolation. Thereafter, the apertures of the pilot fuel flowrate control valve 19, the top hat fuel flow rate control valve 21, andthe main fuel flow rate control valve 17 are controlled based on therespective fuel gas ratios (the pilot ratio, the top hat ratio, and themain ratio), which are determined based on this CLCSO. In this way, thefuel supplies to the respective fuel nozzles (the pilot nozzle 25, thetop hat nozzle 27, and the main nozzle 26) are controlled. Accordingly,it is possible to perform the control based on the combustion gastemperature at the inlet of the gas turbine in conformity to theoriginal concept, and to maintain the relations between the CLCSO andthe respective fuel gas ratios (the pilot ratio, the top hat ratio, andthe main ratio), i.e. the relations between the combustion fuel gastemperature and the respective gas ratios (the pilot ratio, the top hatratio, and the main ratio) even if the intake-air temperature, thecombustion gas temperature, and the properties of the combustion fuelgas are changed or if the performance of the gas turbine 1 isdeteriorated. As a result, it is possible to perform appropriatecombustion control. Moreover, the bypass amount Of tie compressed air iscontrolled by regulating the aperture of the combustor bypass valvebased on the computed CLCSO. Accordingly, it is possible to control thecombustor bypass valve 8 based on the combustion gas temperature at theinlet of the gas turbine in conformity to the original concept as well.Moreover, it is possible to maintain the relation between the CLCSO andthe aperture of the combustor bypass valve, i.e. the relation betweenthe combustion gas temperature at the inlet of the gas turbine and theaperture of the combustor bypass valve. As a result, it is possible toperform appropriate combustion control in light of the bypass flowamount control of the compressed air as well. For example, in a case ofcarrying out an IGV opening operation at the constant power generatoroutput (the gas turbine output), it is apparent from operating resultsof the gas turbine as shown in FIG. 39 to FIG. 41 that the pilot ratioand the aperture of the combustor bypass valve follow a decline in thecombustion gas temperature TIT at the inlet of the gas turbineattributable to the IGV opening operation. Moreover, it is also apparentfrom operating results of the gas turbine as shown in FIG. 42 and FIG.43 that a variation in the combustion gas temperature does not cause avariation in the pilot ratio or in the aperture of the combustor bypassvalve.

Moreover, the combustion control device for a gas turbine according tothis embodiment includes the gas turbine output learning circuit 201.The gas turbine output learning circuit 201 has: the means for computingthe first exhaust gas temperature (EXT1400) corresponding to themeasured pressure ratio based on the first characteristic curve (thecharacteristic curve A) representing the relation between the pressureratio of the compressor 4 and the exhaust gas temperature of the gasturbine body 2 when the combustion gas temperature at the inlet of thegas turbine is adjusted to the first combustion gas temperature (1400°C.) at the inlet of the gas turbine; the means for computing the secondexhaust gas temperature (temperature controlled EXT) corresponding tothe measured pressure ratio based on the second characteristic curve(the characteristic curve B) representing the relation between thepressure ratio and the exhaust gas temperature when the combustion gastemperature at the inlet of the gas turbine is adjusted to the secondcombustion gas temperature (1500° C.) at the inlet of the gas turbine,which is higher than the first combustion gas temperature (1400° C.) atthe inlet of the gas turbine; the means for computing the thirdcombustion gas temperature (TIT) at the inlet of the gas turbinecorresponding to the measured pressure ratio and the measured exhaustgas temperature by linear interpolation based on the first combustiongas temperature (1400° C.) at the inlet of the gas turbine, the secondcombustion gas temperature (1500° C.) at the inlet of the gas turbine,the first exhaust gas temperature (EXT1400), the second exhaust gastemperature (temperature controlled EXT), and the measured exhaust gastemperature (EXT);, the means for computing the third gas turbine output(the temperature controlled MW) corresponding to the third combustiongas temperature (TIT) at the inlet of the gas turbine by linearinterpolation based on the first gas turbine output (1400° C.MW)corresponding to the first combustion gas temperature (1400° C.) at theinlet of the gas turbine and the second gas turbine output (1500° C.MW(the temperature controlled MW)) corresponding to the second combustiongas temperature (1500° C.) at the inlet of the gas turbine, both gasturbine outputs being computed by gas turbine output computing means,the first combustion gas temperature (1400° C.) at the inlet of the gasturbine, the second combustion gas temperature (1500° C.) at the inletof the gas turbine, and the third combustion gas temperature (TIT) atthe inlet of the gas turbine; and the means for correcting the first gasturbine output (1400° C.MW) and the second gas turbine output (1500° C.MW (the temperature controlled MW)) used for computation of the thirdgas turbine output (the temperature controlled MW) so as to match withthe third gas turbine output (the temperature controlled MW) with themeasured gas turbine output (the power generator output) by comparingthe third gas turbine output (the temperature controlled MW) with themeasured gas turbine output (the power generator output). It is,therefore, possible to start learning and to perform correction of thegas turbine output even when continuing the part-load operation withoutraising the combustion gas temperature at the inlet of the gas turbineup to the maximum combustion gas temperature (1500° C.).

Moreover, since the second gas turbine output (the corrected 1500° C.MW(the temperature controlled MW)) corrected by the gas turbine outputlearning circuit 201 is used for computation of the CLCSO by thecombustion load command computing means, it is possible to compute theaccurate CLCSO corresponding to an actual combustion gas temperature atthe inlet of the gas turbine even when continuing the part-loadoperation without raising the combustion gas temperature at the inlet ofthe gas turbine up to the maximum combustion gas temperature (1500° C.).

Meanwhile, according to the combustion control device for a gas turbineof this embodiment, the means for correcting the first gas turbineoutput (1400° C.MW) and the second gas turbine output (1500° C.MW (thetemperature controlled MW)) in the gas turbine output learning circuit201 is configured to correct the first gas turbine output (1400° C.MW)and the second gas turbine output (1500° C.MW (the temperaturecontrolled MW)) in the following process. First, the correcting meanscalculates the correction coefficient while performing any of theproportional-integral operation and the integral operation of thedeviation between the third gas turbine output (the ideal MW) and themeasured gas turbine output (the power generator output), and thenmultiplies each of the first gas turbine output (1400° C.MW) and thesecond gas turbine output (1500° C.MW (the temperature controlled MW))by this correction coefficient. It is, therefore, possible to correctthe first gas turbine output (1400° C.MW) and the second gas turbineoutput (1500° C.MW (the temperature controlled MW)) easily and reliably.

Meanwhile, according to the combustion control device for a gas turbineof tins embodiment, the gas turbine output learning circuit 201 includesany of the means for weighting the deviation between the third gasturbine output (the ideal MW) and the measured gas turbine output (thepower generator output) so as to increase the weighted coefficient usedfor multiplication of the deviation in response to an increase in theCLCSO computed by combustion load command value computing means and themeans for weighting the deviation so as to increase the weightedcoefficient used for multiplication of the deviation in response to theincrease in the third combustion gas temperature (TIT) at the inlet ofthe gas turbine. It is, therefore, possible to correct the gas turbineoutput appropriately in response to the combustion gas temperature atthe inlet of the gas turbine (that is, the gas turbine output) andthereby to correct the gas turbine output promptly while reducinglearning time around the second combustion gas temperature (1500° C.equivalent to the maximum combustion gas temperature) at the inlet ofthe gas turbine.

Note that, application of the gas turbine output learning circuit of thepresent invention is not limited only to the case of correcting the gasturbine output (1500° C.MW (the temperature controlled MW)) used forcomputing the CLCSO by the combustion load command computing means asdescribed above. The gas turbine output learning circuit is alsoapplicable to a case of correcting the gas turbine output for use inother purposes. Specifically, the gas turbine output learning circuit ofthe present invention can be widely used in many cases of performingautomatic correction of gas turbine outputs that are computed by avariety of gas turbine output computing means and that are used forvarious applications while considering deterioration in performances ofthe gas turbines.

Moreover, the embodiment has been described as an example of the gasturbine including the combustor provided with three types of fuelnozzles, namely, a first fuel nozzle (corresponding to the main nozzlein the illustrated example), a second fuel nozzle (corresponding to thepilot nozzle in the illustrated example), and a third fuel nozzle(corresponding to the top hat nozzle in the illustrated example).However, the present invention will not be limited only to thisconfiguration. For example, the present invention is also applicable toa gas turbine including a combustor provided with two types of fuelnozzles (the first fuel nozzle and the second fuel nozzle), and to a gasturbine including a combustor provided with four types of fuel nozzles(the first fuel nozzle, the second fuel nozzle, the third nozzle, and afourth nozzle).

Moreover, the maximum fuel gas temperature is set to 1500° C. in theabove-described embodiment. Needless to say, the maximum fuel gastemperature is not limited only to this level, and it is possible to setthe maximum fuel gas temperature to any other levels such as 1400° C. or1600° C., as appropriate, in the course of gas turbine designingprocesses in light of improvement in efficiency, durability ofinstruments, NOx reduction, and the like.

Further, when the apertures of the fuel flow rate control valves arecontrolled based on the fuel ratios (the pilot ratio, the top hat ratio,and the main ratio) as described above, such controlling means is notlimited only to the means for setting the respective fuel flow ratecontrol valve position command values based on the fuel ratios (thepilot ratio, the top hat ratio, and the main ratio) as described in theembodiment. It is also possible to perform control based on otherarbitrary controlling means.

The present invention relates to a gas turbine output learning circuitand a combustion control device for a gas turbine provided with the gasturbine output learning circuit. The present invention is useful forapplication in a case of automatic correction of a gas turbine outputcomputed by gas turbine output computing means particularly in a gasturbine that is often subjected to part-load operation, whileconsidering the deterioration in performance of the gas turbine.

The invention thus described, it will be obvious that the same way maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. A gas turbine output learning circuit for a gas turbine having a gasturbine body, a combustor, and a compressor, comprising: means forcomputing a first exhaust gas temperature corresponding to a measuredpressure ratio according to a first characteristic curve representing arelation between the pressure ratio of the compressor and an exhaust gastemperature of the gas turbine body when a combustion gas temperature atan inlet of the gas turbine is adjusted to a first combustion gastemperature at the inlet of the gas turbine; means for computing asecond exhaust gas temperature corresponding to a measured pressureratio according to a second characteristic curve representing a relationbetween the pressure ratio and the exhaust gas temperature when thecombustion gas temperature at the inlet of the gas turbine is adjustedto a second combustion gas temperature at the inlet of the gas turbine,which is higher than the first combustion gas temperature at the inletof the gas turbine; means for computing a third combustion gastemperature at the inlet of the gas turbine corresponding to themeasured pressure ratio and a measured exhaust gas temperature by linearinterpolation according to the first combustion gas temperature at theinlet of the gas turbine, the second combustion gas temperature at theinlet of the gas turbine, the first exhaust gas temperature, the secondexhaust gas temperature, and the measured exhaust gas temperature; meansfor computing a third gas turbine output corresponding to the thirdcombustion gas temperature at the inlet of the gas turbine by linearinterpolation according to a first gas turbine output corresponding tothe first combustion gas temperature at the inlet of the gas turbine anda second gas turbine output corresponding to the second combustion gastemperature at the inlet of the gas turbine which are computed by gasturbine output computing means, the first combustion gas temperature atthe inlet of the gas turbine, the second combustion gas temperature atthe inlet of the gas turbine, and the third combustion gas temperatureat the inlet of the gas turbine; and means for correcting the first gasturbine output and the second gas turbine output which are used forcomputation of the third gas turbine output by comparing the third gasturbine output with a measured gas turbine output so as to match thethird gas turbine output with the measured gas turbine output.
 2. Thegas turbine output learning circuit according to claim 1, wherein themeans for correcting the first gas turbine output and the second gasturbine output is configured to correct the first gas turbine output andthe second gas turbine output by calculating a correction coefficientwhile performing any of a proportional-integral operation and anintegral operation of a deviation between the third gas turbine outputand the measured gas turbine output and multiplying each of the firstgas turbine output and the second gas turbine output by this correctioncoefficient.
 3. The gas turbine output learning circuit according toclaim 2, further comprising means for weighting the deviation betweenthe third gas turbine output and the measured gas turbine output so asto increase a weighted coefficient used for multiplication of thedeviation in response to an increase in a combustion load command valueto render the combustion gas temperature at the inlet of the gas turbinecomputed by combustion load command value computing means dimensionlessor means for weighting said deviation so as to increase the weightedcoefficient used for multiplication of the deviation in response to anincrease in the third combustion gas temperature at the inlet of the gasturbine.
 4. A combustion control device for a gas turbine which isfitted to a gas turbine provided with a gas turbine body, a combustorhaving multiple types of fuel nozzles, a compressor installed with aninlet guide vane, and multiple fuel flow rate control valves forrespectively controlling fuel supplies to the multiple types of the fuelnozzles, the combustion control device being configured to control thefuel supplies to the multiple types of the fuel nozzles by controllingapertures of the fuel flow rate control valves, the combustion controldevice comprising: gas turbine output computing means for computing afirst gas turbine output corresponding to a first combustion gastemperature at an inlet of the gas turbine, a second gas turbine outputcorresponding to a second combustion gas temperature at the inlet of thegas turbine being higher than the first combustion gas temperature atthe inlet of the gas turbine, and a fourth gas turbine outputcorresponding to a fourth combustion gas temperature at the inlet of thegas turbine being lower than the second combustion gas temperature atthe inlet of the gas turbine according to an intake-air temperature ofthe compressor and an aperture of the inlet guide vane; and combustionload command computing means for computing a combustion load commandvalue to render the combustion gas temperature at the inlet of the gasturbine dimensionless by linear interpolation according to the secondgas turbine output, the fourth gas turbine output and a measured gasturbine output, wherein the combustion control device controls the fuelsupplies to the multiple types of the fuel nozzles by determining ratiosof fuels to be supplied respectively to the multiple types of the fuelnozzles according to the combustion load command value computed by thecombustion load command computing means, and by controlling apertures ofthe fuel flow rate control valves according to the ratio of the fuels,and the combustion control device for a gas turbine comprises a gasturbine output learning circuit comprising: means for computing a firstexhaust gas temperature corresponding to a measured pressure ratioaccording to a first characteristic curve representing a relationbetween the pressure ratio of the compressor and an exhaust gastemperature of the gas turbine body when a combustion gas temperature atan inlet of the gas turbine is adjusted to the first combustion gastemperature at the inlet of the gas turbine; means for computing asecond exhaust gas temperature corresponding to a measured pressureratio according to a second characteristic curve representing a relationbetween the pressure ratio and the exhaust gas temperature when thecombustion gas temperature at the inlet of the gas turbine is adjustedto the second combustion gas temperature at the inlet of the gasturbine; means for computing a third combustion gas temperature at theinlet of the gas turbine corresponding to the measured pressure ratioand a measured exhaust gas temperature by linear interpolation accordingto the first combustion gas temperature at the inlet of the gas turbine,the second combustion gas temperature at the inlet of the gas turbine,the first exhaust gas temperature, the second exhaust gas temperature,and the measured exhaust gas temperature; means for computing a thirdgas turbine output corresponding to the third combustion gas temperatureat the inlet of the gas turbine by linear interpolation according to thefirst gas turbine output corresponding to the first combustion gastemperature at the inlet of the gas turbine and the second gas turbineoutput corresponding to the second combustion gas temperature at theinlet of the gas turbine, which are computed by the gas turbine outputcomputing means, the first combustion gas temperature at the inlet ofthe gas turbine, the second combustion gas temperature at the inlet ofthe gas turbine, and the third combustion gas temperature at the inletof the gas turbine; and means for correcting the first gas turbineoutput and the second gas turbine output used for computation of thethird gas turbine output so as to match the third gas turbine outputwith the measured gas turbine output by comparing the third gas turbineoutput with a measured gas turbine output and, wherein the second gasturbine output corrected by the gas turbine output learning circuit isused for computation of the combustion load command value by thecombustion load command value computing means.
 5. The combustion controldevice for a gas turbine according to claim 4, wherein the means forcorrecting the first gas turbine output and the second gas turbineoutput in the gas turbine output learning circuit is configured tocorrect the first gas turbine output and the second gas turbine outputby calculating a correction coefficient while performing any of aproportional-integral operation and an integral operation of a deviationbetween the third gas turbine output and the measured gas turbine outputand by multiplying each of the first gas turbine output and the secondgas turbine output by this correction coefficient.
 6. The combustioncontrol device for a gas turbine according to claim 5, wherein the gasturbine output learning circuit comprises means for weighting adeviation between the third gas turbine output and the measured gasturbine output so as to increase a weighted coefficient used formultiplication of the deviation in response to an increase in acombustion load command value to render the combustion gas temperatureat the inlet of the gas turbine computed by the combustion load commandvalue computing means dimensionless or means for weighting saiddeviation so as to increase the weighted coefficient used formultiplication of the deviation in response to an increase in the thirdcombustion gas temperature at the inlet of the gas turbine.
 7. Thecombustion control device for a gas turbine according to claim 6,wherein the gas turbine comprises gas turbine bypassing means forbypassing compressed air to any of the combustor and the gas turbinebody, and the gas turbine output computing means computes the first gasturbine output, the second gas turbine output, and the fourth gasturbine output according to the intake-air temperature of thecompressor, the aperture of the inlet guide vane, and a turbine bypassratio equivalent to a ratio between a total amount of compressed air bythe compressor and a turbine bypass flow rate by the gas turbinebypassing means.
 8. The combustion control device for a gas turbineaccording to claim 6, wherein the gas turbine output computing meanscomputes the first gas turbine output, the second gas turbine output,and the fourth gas turbine output according to the intake-airtemperature of the compressor, the aperture of the inlet guide vane, andan atmospheric pressure ratio equivalent to a ratio between the intakepressure of the compressor and a standard atmospheric pressure oraccording to the intake-air temperature of the compressor, the apertureof the inlet guide vane, the turbine bypass ratio, and the atmosphericpressure ratio.
 9. The combustion control device for a gas turbineaccording to claim 5, wherein the gas turbine comprises gas turbinebypassing means for bypassing compressed air to any of the combustor andthe gas turbine body, and the gas turbine output computing meanscomputes the first gas turbine output, the second gas turbine output,and the fourth gas turbine output according to the intake-airtemperature of the compressor, the aperture of the inlet guide vane, anda turbine bypass ratio equivalent to a ratio between a total amount ofcompressed air by the compressor and a turbine bypass flow rate by thegas turbine bypassing means.
 10. The combustion control device for a gasturbine according to claim 5, wherein the gas turbine output computingmeans computes the first gas turbine output, the second gas turbineoutput, and the fourth gas turbine output according to the intake-airtemperature of the compressor, the aperture of the inlet guide vane, andan atmospheric pressure ratio equivalent to a ratio between the intakepressure of the compressor and a standard atmospheric pressure oraccording to the intake-air temperature of the compressor, the apertureof the inlet guide vane, the turbine bypass ratio, and the atmosphericpressure ratio.
 11. The combustion control device for a gas turbineaccording to claim 4, wherein the gas turbine comprises gas turbinebypassing means for bypassing compressed air to any of the combustor andthe gas turbine body, and the gas turbine output computing meanscomputes the first gas turbine output, the second gas turbine output,and the fourth gas turbine output according to the intake-airtemperature of the compressor, the aperture of the inlet guide vane, anda turbine bypass ratio equivalent to a ratio between a total amount ofcompressed air by the compressor and a turbine bypass flow rate by thegas turbine bypassing means.
 12. The combustion control device for a gasturbine according to claim 11, wherein the gas turbine output computingmeans computes the first gas turbine output, the second gas turbineoutput, and the fourth gas turbine output according to the intake-airtemperature of the compressor, the aperture of the inlet guide vane, andan atmospheric pressure ratio equivalent to a ratio between the intakepressure of the compressor and a standard atmospheric pressure oraccording to the intake-air temperature of the compressor, the apertureof the inlet guide vane, the turbine bypass ratio, and the atmosphericpressure ratio.
 13. The combustion control device for a gas turbineaccording to claim 4, wherein the gas turbine output computing meanscomputes the first gas turbine output, the second gas turbine output,and the fourth gas turbine output according to the intake-airtemperature of the compressor, the aperture of the inlet guide vane, andan atmospheric pressure ratio equivalent to a ratio between the intakepressure of the compressor and a standard atmospheric pressure oraccording to the intake-air temperature of the compressor, the apertureof the inlet guide vane, the turbine bypass ratio, and the atmosphericpressure ratio.